Free Tools
Interactive tools to help you learn and practice. All free, all in your browser.
For Ages 5 to 7
Visit our dedicated K/1 page for tap-friendly tools and labs aligned to K-1 math and NGSS standards.
Original independent MAP Growth Grade 3 Math skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 4 Math skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 5 Math skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 6 Math skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 7 Math skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 8 Math skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original New York Next Generation math practice with concepts, representations, reasoning and written explanations; supplemental post-test topics labeled.
Original Texas TEKS-connected math practice with reasoning, data, hints and written explanations; no official score prediction.
Original California-aligned math concepts, problem solving, reasoning and modeling with linked tasks and explanations; no official score prediction.
Original independent early-grade practice with adult classroom activities and observations; no official score prediction.
Original Grade 6 math practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 7 math practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 8 math practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 4 math skill practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 5 math skill practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 3 math skill questions with hints, explanations, and benchmark links. Independent practice, not official FAST scoring.
Enter any expression and watch it solve step by step following PEMDAS. Each operation is color-coded so you see exactly what happens and why.
See long division worked out step by step with the traditional layout, divide-multiply-subtract-bring-down explanations, and remainder or decimal results.
Type a decimal, fraction, or percent and the other two update instantly. Pie chart, 100-grid, and number line show the same value three ways.
Build visual factor trees, find prime factorizations, and compute GCF and LCM with a Venn diagram of shared prime factors.
Four modes for every percent problem: find the part, the percent, the whole, or percent change. 100-grid and bar model visuals with step-by-step math.
See expanded multiplication, area and volume models, powers tables, and rules for zero and negative exponents. Visual models for squares and cubes.
Add, subtract, multiply, or divide fractions with fraction bar models, area models, and step-by-step solutions. Supports mixed numbers.
Add or subtract integers on a visual number line. Arrow shows direction and distance, with step-by-step explanations for negative number operations.
Solve one-step and two-step equations visually with an SVG balance scale. See step-by-step operations applied to both sides.
Explore ratios with tape diagrams, equivalent ratio tables, unit rates, and cross-multiplication proportion solving.
See any number broken into place values with base-10 blocks, expanded form, and word form. Supports decimals.
Solve ax² + bx + c = 0 with an interactive graph. See roots, vertex, discriminant, and step-by-step solutions.
Solve systems of linear equations with step-by-step Gaussian elimination, interactive matrix visualization, and exact fraction arithmetic.
Explore the unit circle interactively. Drag a point to see trig values, exact forms, and geometric meanings for any angle.
Compute factorials, permutations, combinations, and multinomial coefficients with step-by-step breakdowns and an interactive Pascal's Triangle.
Compute determinants, inverses, row reduction, multiplication, and more with step-by-step solutions.
Solve any triangle with step-by-step Law of Sines and Law of Cosines solutions.
Factor polynomials up to degree 4 and find roots with step-by-step solutions.
Graph and solve linear and quadratic inequalities with number line shading, 2D region visualization, and interval notation.
Add Fourier harmonic terms to approximate square, sawtooth, triangle, and rectified waves. Watch the partial sum converge to the target, see the harmonic amplitude spectrum, and explore the Gibbs phenomenon, the roughly 9 percent overshoot that persists near jump discontinuities no matter how many terms you add.
Add, subtract, scale, dot product, and cross product of 2D vectors with SVG coordinate plane, tip-to-tail and parallelogram methods.
See how a 2x2 matrix transforms a unit square. Visualize rotation, scaling, shearing, and reflection with determinant and eigenvalues.
Evaluate logs in any base, solve log equations, use change-of-base formula, and see the graph with its exponential inverse. Log properties panel included.
Add, subtract, multiply, divide complex numbers with an Argand diagram. See polar form, modulus, argument, and step-by-step math.
Calculate P(A or B), P(A and B), P(not A), and conditional P(A|B) with a Venn diagram and step-by-step formulas.
Solve 2x2 through 5x5 systems with Gaussian elimination. Step-by-step row operations, augmented matrix display, determinant, and solution classification.
Find eigenvalues and eigenvectors of 2×2 and 3×3 matrices. Shows characteristic polynomial, real and complex eigenvalues, normalized eigenvectors, diagonalization matrices P and D, and an interactive eigenvector direction plot.
Visualize span, linear independence, basis, and dimension in ℝ². Input up to 4 vectors, see their span shaded on an interactive graph, check independence, find a basis, and compute Gram-Schmidt orthogonalization.
Factor any number into primes with a branching factor tree and step-by-step division. Animate the Sieve of Eratosthenes up to 500, watching multiples get crossed out by color as primes emerge.
Compute a mod n, modular addition, multiplication, and fast exponentiation. Find modular inverses with the extended Euclidean algorithm, solve systems via the Chinese Remainder Theorem, and visualize clock arithmetic on an interactive number circle.
Build and analyze graphs with draggable SVG nodes. Run BFS and DFS traversals, find shortest paths with Dijkstra's algorithm, compute minimum spanning trees with Prim's algorithm, and detect Eulerian circuits and paths.
Enter elements for 2 or 3 sets and see results highlighted on interactive Venn diagrams. Explore union, intersection, complement, difference, symmetric difference, power set, and Cartesian product with cardinality stats.
Interactive analog and digital clock for learning to tell time, with quarter-hour labels, AM/PM, elapsed time calculator, and schedule puzzles for elementary students
Click coins and bills to count money, practice making change, and compare prices. Interactive US currency tool for elementary students
Explore addition and subtraction with base-10 blocks, number line hops, and the column method. Visualize regrouping and borrowing for numbers up to 999
Explore division through equal sharing and equal grouping models with visual animations, remainder highlighting, and inverse multiplication connections
Explore multiplication with arrays, equal groups, skip counting, and fact families. Visual models for times tables from 1×1 to 12×12
Plot points on a first-quadrant grid, play treasure hunt with coordinate clues, draw shapes by connecting points, and measure distances. Interactive coordinate geometry for elementary students
Round numbers to the nearest 10, 100, or 1000 on an interactive number line. Practice front-end estimation and check if answers are reasonable
Place, compare, and find equivalent fractions on an interactive number line. Visualize unit fractions, mixed numbers, and fraction comparison for elementary students
Interactive fraction wall showing halves through twelfths. Click pieces to find equivalents, compare fractions visually, and simplify with GCD
Shade cells on interactive tenths strips and hundredths grids to build decimal understanding. Compare decimals visually and connect to fraction equivalents
Build Singapore math bar models (tape diagrams) for part-whole, comparison, and multiplicative word problems. Visual problem-solving strategy for elementary students
Virtual ruler, graduated cylinder, and balance scale for practicing measurement. Convert between inches/cm, mL/cups, and grams/kg with visual comparisons
Practice converting between measurement units with visual guides. Learn metric and customary units for length, mass, volume, and time with interactive challenges
Feed numbers through a function machine to discover rules. Single and two-step operations, pattern tables, guess-the-rule puzzles, and number sequence extension
Multiply 2-digit and 3-digit numbers by drawing area models. Break each number into tens and ones, compute partial products in each rectangle, and add them up to find the total.
See fraction multiplication with colorful area models. Shade rows and columns to find the overlap, practice building models, and compare products on a number line.
Build mixed numbers with stepper buttons and watch them decompose into improper fractions with fraction circles or bars. Number line shows both forms. Practice conversions and add/subtract mixed numbers in Challenge mode
Find all factor pairs of a number and see them as rectangular arrays. Explore multiples, identify prime and composite numbers, and discover GCF and LCM with a Venn diagram.
Divide step by step using partial quotients. Subtract friendly multiples, stack the quotients, and find remainders. Practice with word problems that ask what to do with the leftover.
Use base-ten blocks to add, subtract, multiply, and divide decimals. See flats (1), rods (0.1), and unit cubes (0.01) come together with regrouping animations.
Build numerical expressions by clicking number tiles and operator cards. Add parentheses to change the value, match expressions to word descriptions, and explore numerical patterns.
Solve two-step word problems by choosing operations and entering each step. Visual work mat guides students through combine-then-remove, multiply-then-share, and other problem types.
Solve elapsed time problems using interactive analog clocks and a number line jump strategy. Find how long between two times or what time it will be after a duration.
Partition circles, rectangles, triangles, and hexagons into equal shares and identify the unit fraction each part represents. Build fraction models by shading parts.
Build and interpret 'times as many' comparisons using animated bar models. Find the product, base, or multiplier in multiplicative comparison word problems.
Share objects equally among groups and discover that the result is a fraction. Connect division to fractions through pizza, apple, and sandwich sharing stories.
Explore two kinds of unit fraction division: how many 1/4 cups fit in 3 cups, and how to share 1/3 of a pizza among 4 people. Number line and area models support both types.
Solve multi-step measurement word problems with unit conversion. A conversion reference card is always visible. Covers length, mass, capacity, and time in US and metric units.
Determine whether numbers are prime or composite by building all possible rectangular arrays. Sort numbers into Prime and Composite bins and discover that 1 is neither.
Build part-part-whole number bonds and explore all four related addition and subtraction facts. Three difficulty levels for grades K-3.
Explore skip counting patterns on an interactive hundreds chart. Count by 2s, 5s, 10s and more. Watch the pattern light up and fill in missing numbers. Grades K-3.
Explore months, days, and dates on an interactive calendar. Answer questions about days of the week, count days forward and back, and practice date math. Grades K-3.
Drag the thermometer to explore temperatures. See clothing tips and real-world context for hot and cold days. Practice Celsius and Fahrenheit. Grades K-3.
Measure objects using paper clips, erasers, and blocks. See how bigger units mean smaller counts. Practice measurement concepts for grades K-2.
Build numbers on ten-frames, subitize dot patterns, and fill frames to match targets. Build early number sense for numbers 1 to 10. Grades K-1.
Count objects, compare pairs with greater than, less than, or equal, and put numbers in order. Covers K.CC.6, K.CC.7, and 1.NBT.3. Grades K-1.
See teen numbers as 10 plus some ones using ten-rods and unit blocks. Build, identify, and decompose numbers 11 to 19. Grades K-1.
Hop forward and backward on a number path from 0 to 20. Practice counting on, counting back, and early addition and subtraction. Grades K-1.
Record survey data with tally marks and display it as a pictograph. Practice reading charts, comparing counts, and answering data questions. Grades 1-2.
Identify 2D shapes by counting sides and corners. Sort circles, triangles, squares, rectangles, pentagons, and hexagons by their attributes. Grades K-1.
Combine triangles, squares, and semicircles to build larger shapes. See how smaller shapes fit together to compose circles, rectangles, and more. Grades K-1.
Practice above, below, beside, between, left, and right using an animal grid map. Answer positional questions to build spatial vocabulary. Grades K-1.
Practice 1st through 10th with animal line-up games. Identify ordinal positions, place characters in sequence, and solve short ordering stories. Grades K-1.
Place everyday objects on a virtual balance scale and predict which side is heavier, lighter, or equal before it tips. Practice comparing weights with heavier, lighter, and equal. Grades K-1.
Enter prices and quantities for two products to instantly compare cost per unit. A best-buy badge highlights the better value, with savings percentage and preloaded examples like cereal boxes and juice bottles.
Enter an item price, discount percentage, and sales tax rate to see the full price breakdown step by step. Explore whether applying the discount or tax first changes the total. Supports stacked discounts (e.g. 20% off then 8% tax) with a visual flowchart showing each calculation stage and a final price badge.
Compare simple vs compound interest with an interactive savings simulator. Enter principal, annual rate, years, and optional monthly contributions. Toggle compounding frequency (annually, quarterly, monthly, daily). A year-by-year balance chart and table show the growth difference. Includes Rule of 72 calculator and total interest breakdown.
Calculate monthly loan payments, total interest, and view a full amortization schedule. Enter loan amount, APR, and term in months or years. Compare four preset loan types (car, student, mortgage, personal) side by side. Bar chart shows principal vs interest paid each year, and a downloadable amortization table breaks down every payment.
Convert map distances to real-world distances using any scale ratio. Enter a scale like 1:50000 and a map measurement to find the true distance instantly. Works in reverse (real to map) and includes preset scales for common maps, floor plans, and drawings. Area scale and multi-unit output (km, mi, m, ft, cm, in).
Type or paste data values and labels, choose a chart type (bar, line, pie, or pictograph), and see a colorful SVG graph instantly. Auto-calculates mean, median, mode, and range. Supports up to 12 data points, custom colors, and a title. Pictograph uses icon-per-unit display scaled to the data set.
Color the nodes of a graph so no two neighbors match, watch conflicts light up, and find the chromatic number. Use greedy auto-coloring and see how the same idea schedules exams and assigns registers.
Original independent MAP Growth Grade 3 Reading skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 3 Language Usage skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 4 Reading skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 4 Language Usage skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 5 Reading skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 5 Language Usage skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 6 Reading skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 6 Language Usage skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 7 Reading skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 7 Language Usage skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 8 Reading skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 8 Language Usage skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original New York reading and writing practice with passages, evidence, hints and manual written self-review; selected standards and no official score prediction.
Original Texas TEKS-connected reading and writing practice with passages, revision, editing, hints and written self-review; no official score prediction.
Original California-aligned Reading, Writing, Listening and Research/Inquiry practice with hints and written self-review; no official score prediction.
Original independent Grade 10 Reading practice across 13 FAST benchmarks with attributed texts, hints and explanations; no official score prediction.
Original Grade 6 reading practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 6 writing practice with short two-source tasks, planning, download and manual rubric guidance.
Original Grade 7 reading practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 7 writing practice with short two-source tasks, planning, download and manual rubric guidance.
Original Grade 8 reading practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 8 writing practice with short two-source tasks, planning, download and manual rubric guidance.
Original Grade 4 reading skill practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 4 short source-based writing tasks with planning, download and manual rubric review.
Original Grade 5 reading skill practice with benchmark selection, hints and explanations. Independent learning, not official scoring.
Original Grade 5 short source-based writing tasks with planning, download and manual rubric review.
Original Grade 3 reading skill questions with hints, explanations, and benchmark links. Independent practice, not official FAST scoring.
Map any story using the five-stage plot structure. Fill in exposition, rising action, climax, falling action, and resolution with a visual arc diagram. Includes three pre-loaded literary examples.
Browse and quiz yourself on 10 types of figurative language including simile, metaphor, personification, hyperbole, alliteration, and irony. Each device includes definition, tip, and three examples.
Practice arranging scrambled sentences into logical paragraphs. Eight exercises across elementary, middle, and high school levels with hints and explanations.
Explore 40 academic vocabulary words with visual maps showing definition, synonyms, antonyms, etymology, and example sentences. Filter by grade level and print any map.
Browse and quiz on 22 literary devices across five categories: figurative language, sound devices, structure, narrative techniques, and rhetoric. Real literary examples from Shakespeare, Orwell, Steinbeck, and more.
Score student writing across 6 traits using a 4-point rubric. Choose narrative, informational, or argumentative mode, rate Ideas, Organization, Voice, Word Choice, Sentence Fluency, and Conventions, and see total score with grade band.
Read short passages on science, history, and social studies, write your own summary, then compare it to a model summary with key ideas highlighted. Build summarizing skills for grades 5-10.
Organize your argument with a claim, supporting evidence, warrants, counterclaim, and rebuttal. Practice the structure of evidence-based argumentative writing for grades 8-12.
Browse 10 common grammar patterns with definitions, examples, and error corrections. Switch to Practice Mode to identify grammar issues in sentences. Covers subject-verb agreement, modifiers, parallel structure, and more.
Read the same story passage told from first-person, second-person, third-person limited, and third-person omniscient perspectives. Compare how point of view changes the reader's experience.
Explore 14 universal literary themes, match quotes from famous works to themes, and build a theme statement using a guided template. Three interactive modes for grades 7-12.
Map up to four characters across a story's arc using the STEAL method. Track speech, thoughts, effect on others, actions, and looks, plus motivations, conflicts, and an arc-rating timeline for grades 6-10.
Analyze poems for rhyme scheme, meter, and figurative devices. Auto-detect feet (iamb, trochee, anapest, dactyl), tag sound and figurative devices, and explore five public-domain presets for grades 9-12.
Multiple-choice practice for inferring word meaning from surrounding text. Bank of 34 passages covering synonym, antonym, definition, inference, and example clue types for grades 5-9.
Practice identifying informational text structures: cause and effect, compare and contrast, problem and solution, sequence, and description. Learn signal words, practice with 22 passages, and try Challenge mode for grades 6-10.
Spot ethos, pathos, and logos in short example passages, then build your own balanced argument and watch the rhetorical triangle show your mix of appeals. Learn how strong persuasion combines credibility, emotion, and logic.
Build correct MLA and APA citations for books, websites, and journal articles with a live preview, then practice telling proper paraphrasing apart from patchwriting and plagiarism. Learn to credit sources and avoid copying.
Original independent MAP Growth Grade 3 Science skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 4 Science skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 5 Science skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 6 Science skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 7 Science skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original independent MAP Growth Grade 8 Science skill practice with explanations, adjustable difficulty and first-attempt progress; no official RIT score.
Original current New York science practice with models, hypothetical data, investigation reasoning and written explanations; selected standards and no official score prediction.
Original current Texas science practice with models, investigations and evidence across assessed strands; no official score prediction.
Original CA NGSS-connected CAST science practice across physical, life and earth/space science with evidence and engineering tasks; no official score prediction.
Original cumulative Grades 6–8 Science practice across all 94 assessed codes with parent groups, hints and explanations. Separate from FAST.
Original cumulative Grades 3–5 science practice across all 94 assessed codes, with evidence, hints and explanations. Separate from FAST Reading and Math.
Original New York Regents history and government practice with attributed sources, context, civic literacy and enduring-issues reasoning; no official score prediction.
Original Texas social studies practice with historical reasoning, sources, geography, government and economics; no official score prediction.
Practice four map reading skills: cardinal and ordinal compass directions, grid coordinate reading, map symbol identification, and distance scale calculations. Four interactive activities for grades 3-8.
Build interactive timelines of historical events by year, category, and description. Color-coded by event type. Three presets: American Revolution, Civil Rights Movement, and Ancient Civilizations.
Explore the three branches of US government with an interactive civics tool. Learn Congressional and Presidential powers, how checks and balances work, how a bill becomes law, and test knowledge with a quiz.
Plot supply and demand curves on an interactive graph and find the equilibrium price and quantity. Explore price floors, price ceilings, market surplus and shortage with three real-world economic scenarios.
Classify 10 sources as primary or secondary, analyze famous historical documents using the SOAPST framework, and practice generating MLA citations across four guided activities.
Assign historical events to their causal role, long-term cause, trigger, the event, short-term consequence, and long-term consequence, then see the full cause and effect chain. Practice with World War I, the American Revolution, and the Industrial Revolution.
Enter voter blocs with ranked ballots, then run the same votes through plurality, ranked-choice (instant runoff), Borda count, and approval voting. See how the winner can change with the method, with round-by-round runoff and a Condorcet check.
Allocate federal spending across major categories under a revenue constraint, then see the annual deficit or surplus, the national debt projected over years with compounding net interest, and the debt-to-GDP ratio. Uses illustrative round numbers to teach fiscal tradeoffs.
Switch between Mercator, equal-area, and other map projections and see how flattening a round Earth distorts area, shape, and distance. Includes a graticule, Tissot distortion circles, an area-scale-by-latitude readout, and the classic Greenland vs Africa size illusion.
Sort real-world scenarios under the correct form of government: democracy, republic, monarchy, dictatorship, oligarchy, theocracy, and more. Reveals a definition and example for each.
See how each branch of the US government checks the others with vetoes, overrides, judicial review, impeachment, and confirmations. Quiz scenarios plus a full checks matrix.
Move a bill through the US legislative process step by step, from introduction and committee to floor votes, the other chamber, and presidential action with veto and override branches.
Browse all 27 amendments to the US Constitution in plain language and quiz yourself on which amendment protects each right, with a focus on the Bill of Rights.
Explore the major US Supreme Court cases taught in civics and US history. Each case covers the dispute, the ruling, and the constitutional principle, with a matching quiz.
Assign each state's electoral votes and watch the tally race to 270. Shows how a candidate can win the presidency without winning the popular vote.
Sort government powers into federal, state, and shared categories. Learn which level of government holds each power and the constitutional basis behind it.
Compare traditional, command, market, and mixed economies across who decides, private property, and the role of government, then sort scenarios into the right system.
Sort statements into the rights, legal duties, and civic responsibilities of US citizens. Learn the difference between what is protected, what is required, and what is expected.
Learn the left-right political spectrum neutrally. Place general policy positions along the spectrum and see how views on the economy and society are described.
Enter a dataset to see mean, median, and mode on an interactive number line with a balance-point fulcrum, box plot, and step-by-step calculations.
Compute mean, median, mode, standard deviation, and more. Visualize data with interactive box plots and histograms.
Find the best-fit line for paired data. See slope, intercept, correlation, R-squared, scatter plot, and residual analysis.
Explore normal, binomial, Poisson, and uniform distributions. Visualize PDF/CDF plots, compute probabilities with draggable bounds, and find inverse values.
Run z-tests, t-tests, two-sample t-tests, and chi-square goodness-of-fit tests. See test statistics, p-values, critical values, and step-by-step breakdowns.
Calculate confidence intervals for means (z and t) and proportions. See margin of error, critical values, number line visualization, and sample size calculations.
Interactive bell curve with shaded probability regions. Convert between raw scores and Z-scores with numerical integration.
Compute posterior probability with an SVG tree diagram, contingency table, and natural frequency display. Step-by-step Bayes formula.
One-way ANOVA for comparing 2-6 group means. F-statistic, p-value, effect size, summary table, and side-by-side box plots.
Test independence with contingency tables up to 4x4. Chi-square statistic, p-value, Cramer's V, and grouped bar chart.
Enter any dataset to compute quartiles, IQR, five-number summary, and percentile ranks. Visualize the distribution with an interactive dot plot.
Build side-by-side box plots for up to three datasets. Shows Q1, median, Q3, Tukey whiskers, and outlier detection.
Plot x,y data pairs to visualize relationships. Computes Pearson correlation coefficient, r-squared, and fits a linear regression line.
Move the classification threshold on a scored-prediction dataset and watch the confusion matrix, accuracy, precision, recall, specificity, and F1 update in real time. See the ROC curve and AUC sweep across all thresholds, and explore the precision-recall tradeoff and class-imbalance effects.
Draw repeated samples from non-normal populations and watch the sampling distribution become normal. Side-by-side histograms.
Fit linear, quadratic, cubic, exponential, logarithmic, and power models to data. Compare R-squared, residuals, and predict new values with scatter plots.
Enter data and build picture graphs, bar graphs, and line plots. Auto-generated questions test reading and comparing data. Perfect for elementary data literacy
Create line plots from measurement data using fractions. Place X marks on number lines with halves, fourths, and eighths. Answer questions and compute totals from fraction data.
Spin a colorful spinner or roll a die, track your results, and explore what is more likely or less likely to happen. Grades 3-5.
Compute uncertainty propagation through experimental formulas. Choose from sum, difference, product, quotient, power, log, exponential, or generic two-variable presets. See the full propagation formula in KaTeX with partial derivatives. Repeated-measurement mode computes mean, sample standard deviation, standard error of the mean, 95% confidence interval, and a histogram from a list of measurements. Output is rounded to match the leading uncertainty digit (e.g. 12.34 plus or minus 0.05).
Visualize how gradient descent finds the best-fit line on a 2D scatter dataset. Drag points, adjust slope and intercept manually with sliders, or click train to animate gradient descent for ~150 iterations. Live readouts of MSE, R-squared, and distance from the closed-form OLS optimum. Loss curve mini-plot tracks MSE over iterations. Five preset datasets including outlier-corrupted and heteroscedastic data show OLS assumptions and limits.
Pick a population distribution and watch the Central Limit Theorem in action. Draw random samples, plot the means, and see how the sampling distribution becomes normal regardless of population shape.
See how a trend that holds inside every group can reverse when the groups are combined. Adjust the group slopes and separation, then toggle between the split and pooled views to watch Simpson's paradox appear.
Plan a study by balancing effect size, sample size, significance level, and power. See the null and alternative distributions, the Type I and Type II error regions, and the power curve, then read the sample size you need.
Calculate area and perimeter of rectangles, triangles, parallelograms, trapezoids, and circles with SVG visuals and step-by-step formulas.
Visualize complementary, supplementary, vertical angles, and parallel lines with transversals. Color-coded equal angle pairs.
Solve any right triangle from two known sides or angles using the SOH-CAH-TOA ratios, inverse trig, and the Pythagorean theorem, with a to-scale labeled diagram and step-by-step reasoning.
Explore the 30-60-90 and 45-45-90 special right triangles, enter one known side, and get every side in exact radical form and decimals with a to-scale labeled diagram and the 1:1:√2 and 1:√3:2 ratios.
Solve real-world angle of elevation and depression problems by entering any two of the horizontal distance, height, line of sight, or angle, with a to-scale scene and worked trigonometry steps.
Explore 15 classical geometry constructions step by step. Watch animations, drag points, and try constructions yourself.
Explore circles, ellipses, parabolas, and hyperbolas with interactive graphs, equations, foci, and tangent lines.
Calculate surface area and volume for 12 three-dimensional shapes with interactive SVG 3D diagrams, step-by-step KaTeX formulas, and real-world presets.
Five modes for distance and midpoint, slope and line equations, parallel and perpendicular lines, circle equations, and triangle properties. Interactive JSXGraph plot with special points.
Visualize translations, rotations, reflections, dilations, and compositions on a coordinate plane. See original and transformed shapes side by side with JSXGraph.
Solve for any missing side with step-by-step math, see the visual proof with colored squares on each side, generate Pythagorean triples, and extend to 3D distance.
Explore six circle theorems with interactive JSXGraph diagrams. Inscribed angles, tangent-radius, arc length, sector area, chord properties, secant-tangent, and cyclic quadrilaterals.
Calculate and visualize properties of regular polygons from 3 to 20 sides. SVG diagram with interior angles, diagonals, area, perimeter, apothem, and circumradius.
Step-by-step proofs for 18 theorems across 4 categories: Parallel Lines, Triangle Theorems, Congruence and Similarity, and Circle Theorems. SVG diagrams highlight the relevant element at each step.
Input triangle measurements and verify congruence or similarity via SSS, SAS, ASA, AAS, HL, AA, SSS~, and SAS~ criteria. SVG overlay renders both triangles to scale.
Select a 3D shape, adjust dimensions with sliders, and see the unfolded net SVG with color-coded faces. Computes surface area formula and value for cube, prism, cylinder, cone, pyramid, and triangular prism.
Slice a 3D solid with a cutting plane and see the 2D cross-section it forms, with a rotatable 3D view of cubes, prisms, cylinders, cones, pyramids, and spheres for Common Core G-GMD.4.
Click to build shapes on a grid and see area and perimeter update live. Explore how shapes with the same area can have different perimeters. Rectangle mode with formulas
Pack rectangular prisms with unit cubes in an isometric 3D view. Count by layers and connect to the volume formula V = l × w × h
Find lines of symmetry in shapes, create mirror drawings on a pixel grid, and explore pattern block compositions. Visual geometry for elementary students
Drag rays to build angles, classify as acute/right/obtuse/straight/reflex, overlay a protractor to measure, and play angle-matching challenges
Classify 2D shapes by sides, angles, parallel lines, and symmetry. Explore the quadrilateral family tree with sorting games and true-or-false quizzes.
Measure angles with an interactive protractor, decompose angles into two parts, and solve unknown-angle puzzles. Explore right angles, straight angles, and full turns.
Explore how 2D nets fold into 3D shapes. Count faces, edges, and vertices. Match nets to cubes, prisms, pyramids, and more. Grades 3-5.
Drag a triangle's vertices and watch the four classical centers update live: centroid, incenter, circumcenter, and orthocenter. See the Euler line through the centroid, circumcenter, and orthocenter, plus the circumcircle and incircle.
Explore which regular polygons tile the plane and view regular and semi-regular tessellations, with the 360 degree vertex rule and Archimedean vertex configurations shown for each tiling.
Plan a geometry city of 3D shapes, see faces, edges, and vertices, compute area and volume, and print to-scale nets with glue tabs.
Plot Cartesian, polar, and parametric curves with trace, curve stats, and step-by-step derivative analysis.
Plot f(x), f'(x), and F(x) together. Drag a point to see the tangent line slope and accumulated area with step-by-step differentiation.
Explore arithmetic and geometric sequences with terms, partial sums, and convergence analysis.
Graph roses, cardioids, Lissajous curves, cycloids, and more with animated tracing and area/arc length computation.
Approximate definite integrals with left, right, midpoint, and trapezoidal methods. Slider for number of rectangles shows convergence.
Select from 23 preset examples across 8 rule categories. See the problem, rule applied, and full worked solution with KaTeX-rendered steps.
Work through u-substitution with 20 examples in 5 categories. Step-by-step reveal shows substitution, du setup, integration, and back-substitution.
12 classic related-rates problems with live SVG diagrams. Enter the known rate and current measurement, then see the computed unknown rate with solution steps.
12 constrained optimization problems with interactive SVG diagrams. Drag the slider or type the variable value and see objective function and derivative plotted live.
Compute left-hand, right-hand, and two-sided limits numerically. SVG graph, approach table, and discontinuity classification.
Evaluate indeterminate-form limits with L'Hopital's rule, seeing the form identified and the numerator and denominator differentiated step by step, with a numeric check and a plot near the limit point.
Solve separable, first-order linear, and second-order constant coefficient ODEs. Slope fields, solution curves, characteristic equation analysis, and step-by-step math.
Plot 3D surfaces, parametric curves, vector fields, and implicit surfaces with animation and shareable URLs
Plot slope fields for first-order ordinary differential equations dy/dx = f(x, y). Choose from 13 preset equations including exponential growth, logistic, sinusoidal, and saddle systems, or type your own expression with sin, cos, exp, log, sqrt, and abs. Click anywhere on the canvas to draw a solution curve through that initial condition using fourth-order Runge-Kutta integration both forward and backward. Adjustable grid density and step size.
Visualize how a Taylor or Maclaurin polynomial approximates a function and where the error comes from. Adjust the degree and expansion center, compare the pointwise error to the Lagrange remainder bound, and see why the approximation breaks outside the radius of convergence.
Step through Newton's method to find a root of a function by following tangent lines to the x-axis. Pick a function and starting guess, watch the iterates converge, and see the classic failure modes when the derivative is zero, the iterates cycle, or the method diverges.
Compute the arc length of a curve y = f(x) and the surface area generated by revolving it about the x-axis or y-axis. See the arc length integral and the surface of revolution integral with live values, and a schematic of the revolved surface.
Compute the partial derivatives and gradient vector of a multivariable function at any point and see it drawn on a contour plot pointing in the direction of steepest ascent.
Visualize the Mean Value Theorem and Rolle's Theorem by drawing the secant over an interval and finding every interior point where the tangent is parallel to it, with a hypotheses check.
Find dy/dx for an implicit curve with full step-by-step differentiation, then evaluate the slope at a point and see the tangent drawn on the curve.
Work through integration by parts and partial-fraction decomposition step by step, with a numeric check that the antiderivative matches the definite integral.
Analyze a function with the first and second derivative tests to find critical points, increasing and decreasing intervals, concavity, and inflection points, all marked on the graph.
Calculate trajectory, range, max height, and time of flight for projectile motion. Visualize the parabolic path with an interactive time slider and velocity vectors.
Calculate voltage, current, resistance, and power with Ohm's law. Build series and parallel resistor networks with step-by-step equivalent resistance.
Visualize image formation with interactive ray diagrams for lenses and mirrors.
Solve constant-acceleration problems with step-by-step solutions and motion graphs.
Visualize transverse waves, superposition, interference, and standing waves.
Visualize two-source interference patterns, thin-film colors, and beats with animated canvas and path-difference analysis.
Explore Newton's second law with interactive free-body diagrams on surfaces, inclines, and more.
Add vectors graphically and by components, resolving each into x and y parts and finding the resultant magnitude and direction on a coordinate plane.
Simulate elastic, inelastic, and partially inelastic 1D collisions with energy analysis.
Visualize refraction, total internal reflection, and critical angles with an interactive ray diagram.
Track kinetic, potential, and spring energy as an object moves along ramps, roller coasters, and spring systems.
Animate mass-spring and pendulum systems with damping modes, displacement graphs, and phase portraits.
Calculate gravitational force, field strength, orbital velocity, and escape velocity with an SVG force diagram and step-by-step math.
Compute centripetal acceleration and force, period, frequency, and angular velocity for circular motion, plus banked-curve angle and minimum speed in a vertical loop, with a vector diagram.
Solve Q=mcΔT for any variable or find the equilibrium temperature when mixing two substances. Step-by-step thermal energy math.
Calculate linear, area, and volume thermal expansion of a material for a temperature change, with material coefficients and a diagram of the original and expanded object.
Visualize exponential decay with an SVG curve and atom grid. Compute remaining quantity, decay constant, and activity for common isotopes.
Compute the mass defect and nuclear binding energy of a nuclide from its protons, neutrons, and mass, with the binding-energy-per-nucleon curve marking where the nuclide sits relative to the iron peak.
Compute Lorentz factor, time dilation, and length contraction at relativistic speeds. Includes twin paradox scenario and γ vs v/c curve.
Calculate perceived frequency shift with SVG wavefront visualization. Handles approaching and receding sources with Mach number detection.
Place positive and negative charges on a canvas. See electric field arrows, field lines, and potential color maps update in real time.
Calculate force on a current-carrying wire or moving charge in a magnetic field. SVG diagram with right-hand rule visualization.
Shine light on metals and observe electron emission. Adjust frequency and intensity to discover Einstein's photoelectric equation.
Calculate torque, moment of inertia for common shapes, angular acceleration, and rotational kinetic energy with an SVG force diagram.
Four-mode rotational mechanics tool covering moment of inertia (10 shapes), angular momentum and dynamics, rolling without slipping on inclines, and rotational equilibrium with SVG visualizations.
Apply Bernoulli's equation and the continuity equation to solve for pressure, velocity, or height at two points in a fluid flow with pipe visualization.
Calculate electrostatic force with Coulomb's law, parallel plate capacitance, and series/parallel capacitor combinations with SVG diagrams and step-by-step math.
Convert between frequency, wavelength, and energy. Interactive EM spectrum bar from radio to gamma rays with Wien's displacement law for blackbody radiation.
Calculate mechanical advantage, effort force, and efficiency for fixed, movable, compound, and multiple pulley systems. SVG diagrams show rope paths and force arrows.
Configure upper and lower pulley blocks with 1-4 sheaves, toggle rope anchor, and see how compound friction affects a real block and tackle. Dynamic SVG rope threading diagram.
Calculate speed ratios, torque, belt tension, belt length, and power for belt-driven systems. Animated SVG shows two pulleys connected by a belt rotating at correct relative speeds.
Calculate gear ratios, output speed, and torque for simple gear pairs, compound gear trains (up to 4 pairs), and planetary epicyclic systems. Animated SVG shows meshing gear teeth rotating at correct relative speeds.
Visualize a particle's wave function tunneling through a potential barrier. Adjust energy, barrier height, and width to see transmission and reflection coefficients with exact formulas and animated waves.
Visualize hydrogen electron orbitals with a 2D probability density heatmap. Select quantum numbers (n, l, m) to see orbital shapes, radial probability plots, energy levels, and node structure.
Calculate orbital parameters with Kepler's laws, escape velocities for any solar system body, and Hohmann transfer orbits. SVG orbit diagrams, step-by-step formulas, and planetary data.
Analyze transient and AC steady-state behavior of RC, RL, and RLC circuits. Visualize voltage and current vs time, impedance resonance curves, damping classification, and step-by-step formulas.
Compare ideal (no drag) vs real (with drag) projectile trajectories side by side. RK4 numerical integration computes the drag trajectory. Calculates terminal velocity, range reduction, and time of flight difference for presets including baseball, golf ball, cannonball, tennis ball, feather, and skydiver.
Analyze forced oscillations with viscous damping. Plot the resonance curve (amplitude vs driving frequency), time-domain transient response, and steady-state amplitude. Adjust mass, stiffness, damping, force amplitude, and driving frequency. Classifies underdamped, critically damped, and overdamped regimes. Presets for car suspension, earthquake damper, and high-Q resonance.
Four modes: pressure basics (P = F/A) with unit conversions, hydrostatic pressure at depth (P = P₀ + ρgh), Pascal's law hydraulics with mechanical advantage, and atmospheric pressure vs altitude. SVG hydraulic press diagram, depth gradient, and altitude bar. Presets for deep ocean, hydraulic car lift, blood pressure, tire pressure, and scuba diving.
Explore Gauss's Law with five charge distributions: point charge, infinite line, infinite plane, uniformly charged sphere, and uniformly charged cylinder. SVG cross-section visualization, E(r) graph, step-by-step KaTeX derivation, and presets for inside/outside Gaussian surfaces.
Visualize magnetic fields from straight wires, current loops, solenoids, and parallel wires. Calculate B-field magnitude at a probe point, see 2D field line patterns, right-hand rule reminders, and step-by-step Biot-Savart and Ampere's Law derivations.
Sort 16 common materials by properties like hard/soft, transparent/opaque, and conductor/insulator. Venn diagram mode for two-property sorting. Best-use challenges
Watch particles change behavior as temperature changes. See solids melt to liquids and boil to gases with animated particles, heating curves, and property comparisons
Push objects across different surfaces to see how force and friction affect motion. Compare ice, wood, grass, carpet. Explore balanced and unbalanced forces
Explore levers, ramps, pulleys, and wheel-and-axle with interactive simulations. Adjust parameters to see how simple machines reduce effort. Pick-the-best-machine challenges
Explore sound waves with frequency and amplitude sliders, create shadows with different materials, see light reflection angles, and mix RGB colors
Build circuits with batteries, bulbs, switches, and wires. Test materials as conductors or insulators. Compare series and parallel circuits with brightness and removal tests
Design and test bridges, boats, towers, and parachutes with the engineering design process. Adjust materials and shapes, compare designs, and improve your score
Drag bar magnets to see attraction and repulsion. Test everyday objects for magnetism and solve design challenges with magnets.
See how energy moves from one object to another. Explore heat, sound, and light energy transfers, then run collision experiments to see how speed and mass affect motion.
Build energy conversion chains from solar panels to speakers. Discover how energy transforms from one form to another without ever disappearing. Grades 3-5.
Classify materials as transparent, translucent, or opaque and predict shadow strength. See how clear glass, frosted glass, wood, and more interact with light. Grades K-1.
Design flashlight, drum, and cup-phone devices that send messages using light, sound, and vibration. Build signal patterns and see what the receiver decodes. Grades K-1.
Compare how fast light, fiber optic signals, sound, jets, and people travel between any two cities. Light circles Earth 7.5 times per second.
Calculate your actual speed through the universe from Earth's rotation, orbital motion around the Sun, and our solar system's journey through the Milky Way.
Launch a rocket from Earth and watch whether it orbits, escapes into space, or crashes back. Adjust velocity and angle to explore orbital mechanics across different planets.
Discover how high and far you could jump on every planet, moon, and dwarf planet. Compare jump height, hang time, long jump distance, and your weight across 14 solar system bodies.
Choose a beam, arch, or suspension bridge template, add truss reinforcement, apply a test load, and see color-coded stress visualization with pass or fail result. Compare max load capacity across all configurations.
Calculate mechanical advantage, efficiency, and output force for all six classic simple machines. Adjust friction to compare ideal (IMA) vs actual (AMA) performance. Covers lever, inclined plane, pulley, wheel-axle, wedge, and screw.
Move a frequency slider from 20 to 2000 Hz and hear the tone play through Web Audio. Animated waveform shows how frequency and amplitude relate to pitch and loudness, with pitch zone labels and real-world examples.
Toggle red, green, and blue spotlights to mix additive light and see how colors combine. Switch to paint mode for subtractive mixing. Overlap zones update in real time showing the resulting color name.
Change tooth counts on two meshing gears and instantly see RPM ratio, output torque, and mechanical advantage. Animated gears spin to show the speed and direction trade-off. Presets from 1:1 to 3:1.
Pick a latitude, day of year, tilt, and azimuth to see daily energy output on your solar panel. An hourly irradiance curve and optimal tilt hint help find the best angle for any location.
Aim a laser pointer to hit a target by placing plane mirrors at 45° angles. Five puzzle levels with increasing complexity. Ray tracing computes exact reflection paths using angle of incidence equals angle of reflection. Displays incidence and reflection angles for each mirror, beam length, and a success/fail result when the beam reaches or misses the target.
Drag weights onto a seesaw to explore how torque and lever balance work. Supports Class 1, Class 2, and Class 3 levers with adjustable fulcrum position. Displays net torque, mechanical advantage, and the balance equation F1d1 = F2d2 using KaTeX. A tilt animation shows the seesaw angle based on net torque, and the balancing force required to achieve equilibrium is calculated live.
Vary angle of attack, airspeed, wing area, air density, camber, and thickness to see lift force, drag force, and lift coefficient curves. NACA 4-digit airfoil renders with airflow streamlines, lift and drag vectors, and a stall warning when angle of attack exceeds the stall angle. Three plots show the C_L vs alpha curve, L/D ratio, and drag polar. Altitude presets for sea level, 5 km, 10 km, and 15 km.
Multi-stage rocket simulator using the Tsiolkovsky equation. Configure 1-3 stages with dry mass, propellant mass, ISP, and TWR; pick payload mass; observe per-stage and total delta-v plus altitude trajectory. Real-rocket presets include Falcon 9, Saturn V, Space Shuttle, and an educational rocket. Compares total delta-v to LEO, lunar transfer, and escape velocity targets.
Explore wave interference and diffraction interactively. Drag two coherent sources to see standing patterns, or simulate Young's double-slit and single-slit diffraction with adjustable wavelength, slit separation, and screen distance.
Watch wavefronts compress in front of a moving source and stretch behind it. Adjust source speed through subsonic, sonic, and supersonic to see Mach cones form. Live frequency shift readouts for sound, water, and light waves.
Method of joints for 5 classic trusses (Pratt, Warren, Howe, Fink, K). Solves reactions and member forces with a colored FBD.
Practice AP Physics 1, 2, and C free-response questions with live rubric grading. Eight multi-part stems across kinematics, forces, energy, momentum, rotation, RC circuits, electrostatics, and magnetism. Per-part feedback with model answers and AP score band estimate.
Build series-diode, LED, NPN common-emitter, NMOS switch, and CMOS inverter circuits. Solve the operating point with Newton iteration, plot family I-V curves with a load-line marker, and trace switching transfer characteristics.
Pick a semiconductor (silicon, germanium, GaAs, GaN) and adjust temperature and doping to see the band diagram, Fermi level, intrinsic carrier concentration, and conductivity. The band gap also sets the LED color and wavelength it would emit and its suitability for solar cells.
Enter your weight and instantly see how much you would weigh on the Sun, Moon, Mars, Jupiter, and every planet. Learn why gravity changes your weight but never your mass.
Calculate density, mass, or volume with the density formula, convert between units, compare common materials, and predict whether an object floats or sinks in water and other fluids.
Plot the Maxwell-Boltzmann speed distribution for a gas at any temperature and molar mass, with the most probable, mean, and rms speeds marked and a second curve to compare.
Interactive periodic table with all 118 elements. Search by name or symbol, compare elements side-by-side, and view by category, electronegativity, phase, or orbital block.
Enter any chemical formula to compute molar mass, element breakdown with mass percentages, and step-by-step calculations. Supports parenthesized groups.
Solve PV=nRT for any variable with unit support for pressure, volume, and temperature. Gas particle visualization and step-by-step math.
Enter pH, pOH, [H+], or [OH-] to compute all four. Color-coded pH scale bar, acid/base classification, and step-by-step KaTeX.
Three modes: compute molarity from mass, dilution M1V1=M2V2, and solution preparation. Beaker visualization and step-by-step math.
Convert a solution between molarity, molality, mole fraction, mass percent, ppm, and ppb from the solute and solvent masses and the solution density, with the formula shown for each unit.
Enter an unbalanced chemical equation and get integer coefficients, color-coded atom counts, and step-by-step verification that every element balances.
Practice naming and writing formulas for ionic compounds, covalent molecules, and acids, with a learn mode that breaks down each rule and a scored practice quiz.
Pick a reaction and watch it break down from the molecular equation to the complete ionic equation to the net ionic equation. Strong electrolytes split into ions, spectator ions are highlighted and cancelled, and the final net ionic equation is checked for atom and charge balance. Covers precipitation, acid-base, gas-forming, and single-displacement reactions.
Look up any of the 118 elements to see full electron configuration, noble gas shorthand, orbital box diagram, valence electrons, and oxidation states.
Enter a substance and quantity in grams, moles, molecules, or liters at STP to convert between all units with a mole map and dimensional analysis.
Compare the effusion and diffusion rates of two gases with Graham's law, finding the rate ratio, time ratio, and an unknown molar mass from a measured rate ratio.
Enter a molecular formula to generate its Lewis structure with bonds, lone pairs, VSEPR geometry, and bond angles. Step-by-step valence electron counting.
Enter a chemical reaction to assign oxidation numbers, identify what is oxidized and reduced, and find oxidizing and reducing agents with electron transfer count.
Trace the complete radioactive decay series for U-238, U-235, and Th-232. See each isotope step with decay mode, half-life, and energy on a cascade diagram or N-Z nuclide chart.
Calculate boiling point elevation, freezing point depression, osmotic pressure, and vapor pressure lowering for any solution. Supports water, benzene, camphor, and more solvents with preset solutions like NaCl, antifreeze, and IV saline.
Select two elements to see electronegativity difference, bond type (nonpolar covalent, polar covalent, or ionic), dipole moment in Debye, percent ionic character, and partial charges. Interactive SVG shows electron density cloud shifted toward the more electronegative atom.
Compare molecules by polarity, molar mass, and hydrogen bonding to predict relative boiling and melting point trends.
Identify and highlight functional groups in organic molecules, alcohols, aldehydes, ketones, carboxylic acids, esters, amines, and more, with IUPAC naming hints.
Select a VSEPR molecular geometry to see a 3D perspective SVG rendering with bond angles, lone pairs, and atom labels. Drag to rotate. Covers all 10 geometries: linear, bent, trigonal planar, tetrahedral, octahedral, and more. Includes preset molecules (H2O, NH3, CH4, SF6, PCl5).
Four equilibrium chemistry modes: build ICE tables and solve for equilibrium concentrations, compare reaction quotient Q to K and predict shift direction, calculate molar solubility from Ksp with optional common ion effect, and solve weak acid/base Ka or Kb for pH and percent ionization. Step-by-step solutions with KaTeX.
Interactive titration curve tool for strong acid-strong base, weak acid-strong base, weak base-strong acid, and diprotic acid titrations. See real-time pH curve, buffer regions, Henderson-Hasselbalch equation, equivalence points, buffer capacity, and indicator color overlays.
Interactive P-T phase diagram for water, CO₂, ethanol, and nitrogen. Click to identify phases, view heating curves at any pressure, explore triple and critical points, apply Clausius-Clapeyron to shift boiling points, and see colligative effects of dissolved solutes on phase boundaries.
Explore the particle model of matter with animated solids, liquids, and gases. Dissolve materials and check conservation of mass. Decide if mixing makes a new substance or not.
Drag substances into solid, liquid, or gas zones. Visual particle animations show spacing and motion for each state. Three difficulty levels work through 6 to 12 substances with hints and a final score.
Click any element family on a color-coded periodic table to highlight all members, explore shared properties, and see real-world examples. Nine families from alkali metals to noble gases.
Drag particle sets into three classification zones (element, mixture, compound) and receive instant feedback. Ten preset particle sets including O2, H2O, NaCl, CO2, salt+water, sand+water, and air. SVG diagrams show atom types and bonds with color-coded circles. Score counter, homogeneous/heterogeneous distinction, and separation method badges. Three difficulty presets.
Predict and build a tower of six liquids (honey, corn syrup, dish soap, water, vegetable oil, rubbing alcohol) ordered by density. Drop six floating objects (grape, Lego brick, ping pong ball, steel bolt, wood chip, ice cube) to see where each settles based on its density vs surrounding liquids. Score your predictions before and after the pour.
Three-tab atomic builder. Atom tab: adjust proton/neutron/electron counts (H through Ca) to see Bohr model SVG, element name, isotope notation, electron configuration, and ion charge. Molecule tab: explore 8 preset molecules (H2, O2, H2O, CO2, NH3, CH4, NaCl, HCl) with SVG structural diagrams and bond type info. Ion tab: click common ions to see why each forms its specific charge.
Slide a pH scale (0.0-14.0) and watch three indicator strips change color: universal indicator, litmus, and red cabbage. Real-world examples appear near the current pH (battery acid, lemon juice, coffee, water, baking soda, bleach). Displays H+ and OH- concentrations in scientific notation plus a safety badge. Neutralization tab shows two reagents combining with a result pH and chemical equation.
Verify the law of conservation of mass using six preset chemical reactions (baking soda + vinegar, iron rusting, hydrogen + oxygen, carbon combustion, copper + silver nitrate, sodium + water). SVG two-pan balance tilts when reactant and product masses differ. Edit reactant masses to simulate open-system mass loss (e.g. CO2 escaping). Percent error display + molar mass calculator.
Choose one of 8 mixtures (sand+water, salt+water, iron filings+sand, oil+water, gravel+sand+salt, alcohol+water, milk+cream, coffee) and apply one of 5 separation methods (filtration, evaporation, distillation, magnetism, decanting). SVG animations show each process. Success or failure feedback with a kid-friendly explanation of why the method works or does not work.
Select two elements from a 20-element grid and see whether they form ionic, polar covalent, nonpolar covalent, or metallic bonds based on electronegativity difference (Pauling scale). SVG bond animation shows electron transfer for ionic bonds and shifting electron cloud for covalent bonds. Displays bond energy, bond length, polarity arrow, and a real molecule example.
Interactive 3D viewer for seven common crystal lattices. Rotate, zoom, and pan with mouse or touch. Includes simple cubic, body-centered cubic, face-centered cubic, diamond, hexagonal close-packed, NaCl rock salt, and CsCl. Toggle bonds, unit-cell edges, and 1x1x1 vs 2x2x2 supercell views. Info panel shows Bravais classification, lattice parameters, packing efficiency, atoms per unit cell, and real-world examples.
Build galvanic or electrolytic cells from a table of 30+ standard reduction potentials. Pick anode and cathode, see E°cell, the auto-balanced overall equation in KaTeX, Gibbs free energy, equilibrium constant, and spontaneity verdict. SVG schematic shows two beakers, salt bridge, voltmeter or external battery, and electron flow direction. Includes Nernst equation reference and real-world applications.
AP-level analyzer for weak-acid titration data. Choose a curated acetic, formic, hypochlorous, or diprotic acid dataset, or paste your own (V, pH) data. Computes first and second derivatives, finds the equivalence point at peak |dpH/dV|, locates the half-equivalence point, and extracts pKa and Ka. Handles diprotic acids with two pKa values.
Find the empirical formula from percent composition or mass, get the molecular formula from the molar mass, and calculate the percent composition of any chemical formula. Shows every step.
Count the significant figures in any number, round to a chosen number of sig figs, and apply the sig-fig rules to addition, subtraction, multiplication, and division. Every step explained.
Calculate the average atomic mass of an element as the abundance-weighted mean of its isotopes, with a reverse mode to solve for an unknown abundance and presets for common elements.
Convert between binary, decimal, hexadecimal, and octal. Bit-level visualization, ASCII lookup, and step-by-step conversion methods.
Enter Boolean expressions with AND, OR, NOT, XOR, and IMPLIES to generate complete truth tables. Detects tautologies and contradictions.
Watch bubble, selection, insertion, merge, and quick sort in action with color-coded bars for comparisons, swaps, and sorted elements.
Compare O(1), O(log n), O(n), O(n log n), O(n^2), O(n^3), and O(2^n) on an interactive graph. See operation counts at any input size.
Select predefined circuits with AND, OR, NOT, XOR, NAND, NOR gates. Toggle inputs and see outputs update in real time with auto-generated truth tables.
Enter a regex pattern and test string to see highlighted matches, capture groups, match count, and a plain-English pattern explanation in real time.
Visualize BFS, DFS, Dijkstra, and A* on an interactive grid. Draw walls, set weighted cells, generate mazes, and watch each algorithm explore step by step.
Visualize stacks, queues, linked lists, binary search trees, and min heaps with animated operations. Push, pop, insert, delete, and traverse step by step.
Build and test finite state machines (DFA/NFA). Create states, define transitions, and test input strings with step-by-step animation showing the machine processing each symbol.
Build a binary search tree and watch inorder, preorder, postorder, and level-order traversals step by step with animated SVG node highlighting and numbered visit badges.
Visualize packet routing through network topologies. Animate Dijkstra's shortest path, explore TCP/IP layers, simulate traceroute, test fault tolerance by disabling nodes, and fragment packets.
Explore Run-Length Encoding and Huffman coding for text, and pixel-level image compression. Build Huffman trees, paint pixel grids, compare lossless vs lossy compression ratios.
Visualize Java arrays, ArrayLists, and 2D arrays step by step. Selection sort, insertion sort, binary search, and all ArrayList methods with animated operations and Java code.
Encrypt and decrypt messages with Caesar, substitution, Vigenère, XOR, and simplified RSA ciphers. Visualize step-by-step encryption, frequency analysis, brute force attacks, and hash avalanche effects.
Step through recursive function execution with animated call stack frames and recursion trees. Visualize factorial, fibonacci, merge sort, binary search, and tower of hanoi with memoization toggle.
Visualize Java OOP concepts with heap/stack memory diagrams. Create objects, make aliases, call methods, and explore reference semantics, scope, and inheritance with step-through execution.
Practice debugging Java code and writing unit tests. Find the bug in 20+ code snippets, write test cases that catch hidden bugs, and browse a reference guide of 16 common Java errors.
Visualize Java String methods interactively. See charAt, substring, indexOf, equals, replace, and more with character-by-character SVG diagrams, == vs .equals() comparison, method chaining, and code tracing.
Guide a robot through a grid by building step-by-step sequences of commands. Learn how computers follow precise instructions - the foundation of all programming.
Build repeat loops to create color tile patterns. Discover how loops let computers do the same action many times without writing the same step over and over.
Build IF/THEN/ELSE rules and watch animated characters respond to changing conditions. Learn how programs make decisions - the heart of all computer logic.
Find and fix bugs in short robot programs. Learn how programmers debug code by reading it step-by-step and testing to see where things go wrong.
Draw pixel art on an 8x8 grid and see how images are stored as numbers. Encode and decode secret messages using the Caesar cipher - A=1, B=2 and a shift.
Make a cat sprite react to clicks, timer ticks, and key presses. Build event rules by picking a trigger and an action, then create a 3-scene animated story.
Sort information cards into safety bins and practice making smart decisions in internet safety scenarios. Learn what is OK to share online.
Watch a message split into numbered packets, travel through routers, and reassemble at the destination. Break a router and see packets reroute.
Classify computer components as input, output, processing, or storage. Explore what breaks when parts are removed and trace paths for common tasks.
Design a survey, tally responses, and explore the results with a live bar graph. Answer interpretation questions about the data. Grades 2–5.
Create named score jars, build a step-by-step program with Add, Subtract, Set, and Reset blocks, then run it and watch the values change. Grades 3–5.
Run the k-means algorithm step-by-step on 2D data. Six preset datasets including blobs, two moons, concentric rings, and anisotropic clusters illustrate where k-means succeeds and fails. Adjust k from 1 to 8, choose random or k-means++ initialization, and watch centroids move as you click step-iterate or run-to-convergence. Live readouts of WCSS inertia and silhouette score. Click to add custom points or load presets.
Three pre-canned scenarios (loan approval, college admissions, resume screening) show how a naive classifier produces unequal outcomes across demographic groups even when overall accuracy is high. Compare naive vs debiased predictions side-by-side with per-group accuracy, true positive rate, false positive rate, and demographic parity gap. Includes four real-world cautionary tales (COMPAS, Apple Card, Amazon hiring, Optum healthcare).
Type any text and watch how a language model breaks it into subword tokens, turns each token into a vector, and links them with self-attention. See token counts, the context window, and causal masking. Tokenization is approximate and the vectors are illustrative.
Write SELECT, JOIN, WHERE, and GROUP BY queries against small sample tables and see the result set plus the logical query plan. A teaching subset of SQL that runs entirely in your browser, no setup required.
Write a tiny assembly program and step through the fetch, decode, and execute cycle. Watch the program counter, registers, memory, zero flag, and output change one micro-step at a time, with labels and conditional jumps.
Run commit, branch, checkout, merge, and rebase on an in-memory repository and watch the commit graph, branches, and HEAD update live. See fast-forward versus three-way merges, merge conflicts, and how rebase rewrites history.
Compute A = P(1+r/n)^(nt) with various compounding frequencies, monthly contributions, growth chart, year-by-year table, and Rule of 72.
Convert across 10 categories: length, mass, volume, temperature, speed, area, energy, pressure, time, and data. See all conversions at once.
Calculate monthly payments, total interest, and generate a full amortization schedule. See the impact of extra payments with principal vs interest charts.
Enter experimental data (x, y pairs) or paste CSV, perform linear regression with R-squared, standard errors, and residual analysis. Propagate uncertainties through addition, multiplication, division, and power operations. Calculate percent error with significant figures. SVG scatter plot with best-fit line and error bars.
Build a personal budget with income and expense categories. Analyze spending with the 50/30/20 rule, visualize cash flow with a waterfall chart, and compare budget scenarios side by side.
Calculate compound growth with contributions, compare real vs nominal returns, see the impact of fees over decades, and use the Rule of 72. Stacked area chart shows principal, contributions, and growth.
Calculate loan payments with the PMT formula, compare avalanche vs snowball debt payoff strategies, and see the true cost of credit card minimum payments with amortization charts.
Maximize or minimize an objective function subject to linear constraints. Visualize the feasible region, evaluate corner points, perform sensitivity analysis, and solve integer programming problems.
Calculate expected value and variance for random outcomes. Build and fold back decision trees to find optimal strategies. Compare insurance plans by expected annual cost and break-even frequency.
Analyze M/M/1 and M/M/c queues with Little's Law. Schedule jobs with FCFS, SPT, EDD algorithms and Gantt charts. Find maximum flow in networks with Ford-Fulkerson and min-cut identification.
Analyze four-bar linkages, crank-slider mechanisms, and cam-follower systems. Compute degrees of freedom, Grashof classification, transmission angles, and trace coupler curves with interactive animation
Test wood, plastic, metal, fabric, paper, and clay against engineering challenges. Discover which materials work best for shelters, bridges, boats, and parachutes. Grades 2-5.
Pick building pieces and stack them into towers, bridges, and pyramids. Discover how triangles add strength and wide bases add stability. Grades K-3.
Choose materials to build a shelter that blocks rain, sun, and wind within a budget. An engineering design challenge introducing K-2 ETS standards. Grades K-2.
Set a monthly income and allocate it across six categories with sliders that always sum to 100 percent. A live pie chart and monthly dollar amounts show how spending choices affect savings.
Allocate a $1000 budget across five bicycle components by choosing quality tiers. A radar chart, overall score, and best-upgrade hint show how trade-offs change performance. Covers speed, safety, durability, comfort, and weight.
Build printable end-of-class exit tickets in seconds. Pick subject, topic, and grade band; choose 3 to 5 questions across multiple choice, short answer, reflection, and self-assessment formats. 528 hand-curated question stems across 8 subjects and 3 grade bands. Includes name and date fields, optional answer key on a separate page, and one-click print, PDF, and copy-as-text export. Mulberry32 seeded randomization keeps the same ticket stable until you regenerate.
Build grading rubrics for any K-12 task in under a minute. Choose from 9 task types (essay, lab report, project, presentation, math problem set, science investigation, code project, group work, generic) and 3-, 4-, or 5-level performance scales. 6 default criteria per task type with hand-written descriptors at every level, adjustable to your grade band. Edit criterion names inline. Export to print, PDF (auto-landscape for 4 plus levels), or CSV for grading.
Build printable practice worksheets in seconds. Pick subject, topic, grade band, count, difficulty, and worksheet style. Math has genuine RNG-based generators (multiplication, fractions, linear equations); other subjects use stem templates. 100+ generator templates total. Mulberry32 seeded PRNG keeps the same worksheet stable until you regenerate. Print, PDF (with answer key page 2), and copy-as-text export.
Sectioned form builder for science lab reports. Fill in title, hypothesis, materials, procedure, data table, graph, analysis, and conclusion. Auto-computed slope and R-squared from your data. Inline SVG line/scatter chart updates as you edit. Print stylesheet, jsPDF multi-page export, and lz-string compressed share link to resume drafts.
Microsim of cars on a closed loop using the Intelligent Driver Model. Adjust car count, road length, desired speed, time headway, max acceleration, and comfortable braking. Optional traffic light with green/red durations. Watch fundamental diagram (density vs flow), space-time diagram trajectories, and throughput in cars per hour. Optimization mode sweeps green-time durations to find the throughput-maximizing setting.
Walk through the seven steps of the engineering design process. Identify a problem, research, brainstorm, design, build, test, and iterate. Save the plan and start your project.
Build a transition matrix, view the state diagram, and watch the distribution converge to the steady state. Run a random walk and see its visit frequencies approach the stationary distribution.
Build a 2x2 game, mark best responses, and find the pure and mixed Nash equilibria and dominant strategies. Then run the iterated prisoner's dilemma between tit-for-tat, grim trigger, and other classic strategies.
Build a basket of goods with quantities, base-year prices, and yearly price changes, then watch the Consumer Price Index rise, see the year-over-year inflation rate, and track how a fixed amount of money loses purchasing power over time. Learn how CPI and real versus nominal value work.
Generate Punnett squares for monohybrid, dihybrid, incomplete dominance, and sex-linked crosses. Color-coded SVG grid with genotype and phenotype ratios and step-by-step analysis.
Read a pedigree chart and work out which inheritance patterns fit, with autosomal and X-linked and Y-linked rules applied and each pattern marked consistent or ruled out.
Simulate exponential, logistic, and Lotka-Volterra predator-prey population models. Interactive JSXGraph plots with carrying capacity, inflection points, phase portraits, and ecological presets.
Transcribe DNA to mRNA and translate codons into amino acid chains. Beautiful sequence diagram with color-coded nucleotides, codon brackets, amino acid pills, full 64-codon table, and reverse translation.
Calculate allele and genotype frequencies, test populations for HW equilibrium with chi-square, and simulate evolutionary forces like selection, drift, mutation, and migration over generations.
Explore Michaelis-Menten enzyme kinetics with interactive plots. Adjust Vmax, Km, substrate concentration, and add competitive, uncompetitive, or noncompetitive inhibitors. View Lineweaver-Burk double-reciprocal plots and temperature/pH activity curves.
Interactive viewer for cell division. Step through every phase of mitosis and meiosis with SVG chromosome visualizations. Track chromosome number (2n vs n), see crossing over and independent assortment in meiosis, and compare both division types side by side. Presets for human (2n=46), fruit fly (2n=8), onion (2n=16), and simple (2n=4) cells.
Explore photosynthesis rates under different light intensities, CO2 concentrations, and temperatures. See light response curves, compensation and saturation points, absorption vs action spectra, and the law of limiting factors.
Explore glycolysis, Krebs cycle, and electron transport chain. Compare aerobic vs anaerobic respiration, calculate ATP yields for glucose, fat, and protein substrates, and see how temperature affects metabolic rate.
Explore MacArthur-Wilson island biogeography, species-area relationships, habitat fragmentation, and diversity indices. Calculate Simpson's D and Shannon-Wiener H' from species count data.
Explore signal transduction cascades, dose-response curves, and feedback loops. Visualize receptor binding, kinase cascade amplification, Hill equation pharmacology, and positive/negative feedback in an interactive diagram.
Align DNA sequences with Needleman-Wunsch and Smith-Waterman algorithms. Translate codons, introduce mutations, compute Jukes-Cantor distances, and build UPGMA phylogenetic trees.
Explore stomatal conductance, transpiration rates, and water potential. Adjust leaf area, stomatal density, humidity, wind, and temperature to simulate potometer experiments and cohesion-tension water transport.
Simulate lac and trp operon regulation, eukaryotic gene expression, and signal-to-expression cascades. Toggle inducers, repressors, and enhancers to see how transcription rates and protein levels respond.
Explore circular plasmid maps with restriction enzyme sites, selectable markers, and gene inserts. Calculate transformation efficiency and visualize fragment sizes from restriction digests.
Digest DNA sequences with restriction enzymes and visualize fragments on a virtual gel. Select from 10 enzymes, perform single or double digests, and estimate fragment sizes from band migration.
Simulate animal behavior in choice chambers. Test phototaxis, hygrotaxis, thermotaxis, and chemotaxis for Drosophila, pillbugs, planaria, and C. elegans with chi-square statistical analysis.
Build energy pyramids and explore the 10% rule of ecological efficiency. Adjust transfer rates across trophic levels, compare energy, biomass, and number pyramids for different ecosystems.
Explore how directional, stabilizing, and disruptive selection reshape trait distributions over generations. Adjust heritability and selection strength to verify the breeder's equation R = h²S.
Watch a bee pollinate flowers and seeds travel the world. Match plants to their dispersal method, then design your own seed with wings, hooks, or floats to see how far it can go.
Set light, water, soil, and temperature conditions to grow virtual bean, sunflower, or grass plants. Compare two plants side by side. Learn what plants need with an interactive checklist
Match 18 animals to 6 habitats (desert, ocean, forest, arctic, grassland, wetland). Explore each animal's adaptations and discover what happens when habitats change
Build food chains and food webs by connecting producers, consumers, and decomposers. See energy flow arrows, auto-classify organisms by role, and simulate what happens when a species is removed
Explore life cycles of butterflies, frogs, flowering plants, and dogs with animated cycle wheels, drag-to-order practice, and side-by-side comparison mode
Interactive ecosystem model showing matter flow between sun, plants, animals, and decomposers. Build food webs, explore organism roles, and simulate what happens when species disappear.
Explore how traits are passed from parents to offspring. Sort traits as inherited or learned, predict offspring features, and discover how the environment can influence appearance.
Tap body parts to learn what they do. Explore how roots absorb water, how eyes detect light, and how fur keeps animals warm. Then design an organism for a challenging habitat.
Follow a signal from your eyes to your brain and back to your muscles. Match senses to sense organs, trace stimulus-response pathways, and compare human senses to incredible animal abilities.
Discover why wolves hunt in packs, penguins huddle in blizzards, and fish school together. Match group behaviors to survival benefits and explore what happens when animals lose their group.
Rescue displaced animals by matching them to their correct habitat and providing food, water, shelter, and space. Discover what every living thing needs to survive. Grades 2-5.
Discover what plants and animals need to survive. Match food, water, shelter, air, sunlight, and space to different living things. Grades K-1.
Match parent animals to their babies, learn baby animal names like puppy, foal, and calf, and discover inherited traits. Grades K-1.
Solve human design problems by copying animal and plant parts. Discover how beaver teeth, gecko feet, and lotus leaves inspire real-world tools. Grades K-1.
Clickable diagram of all 10 human body systems. Tap any system to discover its key organs, function, and a surprising fact — from the circulatory system to the endocrine and immune systems.
Click a food item and follow it through 6 digestive organs (mouth, esophagus, stomach, small intestine, large intestine, elimination). Each stage shows transit time, active enzymes, and how much of each nutrient is absorbed. A nutrient tracker bar chart shows carbs, protein, fat, fiber, and water remaining at each stage. Eight food items including apple, egg, steak, and milk.
Model how the immune system fights four pathogens (influenza, strep, common cold, E. coli) over a 21-day timeline. Compare vaccinated vs unvaccinated outcomes. View innate response (neutrophils/macrophages), B-cell antibody production, and T-cell activation on a multi-line SVG chart. Includes phase timeline, severity score, and estimated clearance day.
Step through the lytic and lysogenic bacteriophage replication cycles stage by stage with labeled diagrams, compare the two paths, and model how lytic infection amplifies virus numbers.
Select donor and recipient ABO/Rh blood types to see transfusion compatibility with a full 8x8 compatibility matrix colored green, yellow (emergency-only), and red. SVG antigen diagram shows A, B, and Rh antigens on red blood cells with matching antibody Y-shapes. Genetics mode shows a 4x4 Punnett square for ABO inheritance with phenotype probability summary.
Click any plant part (roots, stem, leaves, flower, fruit) on an SVG diagram to explore its function, key structures, fun fact, and evolutionary adaptations. Toggle a cross-section view showing xylem and phloem in stem and root. An animated canvas visualization shows blue water molecules moving up through xylem and amber sugar molecules moving through phloem.
Hardy-Weinberg with selection, mutation, drift, and migration acting on a single locus over generations. Track allele frequency p over time. Adjust population size N (with infinite N toggle to disable drift), three genotype fitnesses, forward and backward mutation rates, and migration rate plus source allele frequency. Run 10 stochastic replicates to see drift variance. de Finetti diagram shows the genotype trajectory through the simplex.
Watch a population evolve over generations as selection pressure changes which traits survive. Adjust mutation rate, selection strength, and scenario to see Darwinian evolution in action.
Animated visualization of DNA replication at the fork. Watch helicase unwind the helix, DNA polymerase build the leading strand continuously, primase lay RNA primers on the lagging strand, and ligase seal the Okazaki fragments.
Pick a heart rhythm or set the heart rate and conduction intervals to generate an ECG trace on a clinical grid. Identify the P wave, QRS complex, and T wave, measure the PR, QRS, QT, and QTc intervals, and classify rhythms from normal sinus to bradycardia, tachycardia, AV block, atrial fibrillation, and ventricular tachycardia. For learning, not diagnosis.
Explore labeled animal, plant, and bacterial cell diagrams. Click any organelle to learn its function, quiz yourself on the parts, and compare which structures each cell type has.
Walk a dichotomous key to identify organisms, then explore the full taxonomic classification from domain to species. Compare two species to see where they share a branch.
Explore the four biological macromolecule classes with their monomers, polymers, elements, functions, and the dehydration synthesis and hydrolysis reactions that build and break them.
Set the solution outside a cell and watch which way water moves and how the cell changes in hypertonic, hypotonic, and isotonic conditions. Covers diffusion, osmosis, and passive vs active transport.
Explore the major biomes by climate, plants, animals, and adaptations, then identify a biome from a climate or set of organisms.
Learn mutualism, commensalism, parasitism, predation, and competition by sorting real examples and seeing how each species is affected.
Step through negative and positive feedback loops and watch a regulated variable return to or run away from its set point. Covers body temperature, blood glucose, and more.
Four modes: magnitude scales (Richter Mₗ, moment magnitude M𝑤, energy), energy comparison (each step = 31.6× more energy, logarithmic bar chart), Modified Mercalli Intensity I-XII with descriptions, and Richter magnitude from seismograph amplitude. Presets include Minor M3 through Great M8, 1906 San Francisco M7.9, and 2011 Japan M9.1.
Estimate annual CO₂ emissions from transportation (car miles, fuel type, flights), home energy (electricity, heating, AC), diet (meat consumption, food waste), and lifestyle (shopping, recycling). Pie chart breakdown, country comparison bar chart, trees-to-offset and equivalent-driving metrics. Five presets: Average American, Eco-Conscious, Heavy Commuter, Frequent Flyer, Work from Home.
Three modes: interactive HR diagram with 23 real stars (click to see properties), stellar evolution pathway from nebula to end state (white dwarf, neutron star, or black hole based on initial mass), and star properties calculator (luminosity L∝M^3.5, radius, lifetime t∝M^-2.5, apparent magnitude). Six presets: Sun, Red Dwarf (0.3 M☉), Sirius A (2 M☉), Blue Giant (20 M☉), Betelgeuse (15 M☉), Supergiant (50 M☉). Includes spectral class colour strip and SVG star visualization.
Three modes: plot a single star on the Hertzsprung-Russell diagram from temperature, radius, and mass (Stefan-Boltzmann luminosity, spectral class O-M, absolute magnitude, HR region); compare multiple stars side by side; and browse the spectral atlas with typical properties for each class. 23 reference stars plotted, 6 presets from Proxima Centauri to Rigel.
Two modes: view emission spectra for hydrogen (Balmer series), helium, sodium, neon, and mercury with color-coded spectral lines on a visible-spectrum SVG; and calculate redshift z, recession velocity, Hubble-law distance, and lookback time from rest and observed wavelengths. Six presets from nearby galaxies to quasars.
Compute galactic distance two ways. Distance modulus (Cepheid, Type Ia supernova) and Hubble's Law with a live v vs d diagram.
Two modes: Transit Method calculates transit depth (Rp/R★)², orbital period via Kepler's third law, transit duration, and impact parameter with an interactive SVG showing planet crossing the star disk and light curve. Habitable Zone mode shows inner/outer HZ boundaries, equilibrium temperature, and whether a planet is in the zone with a top-down orbital diagram. Six presets: Earth-Sun, Hot Jupiter, Super-Earth, TRAPPIST-1e, Kepler-22b, Mini-Neptune.
Explore Earth's energy budget and greenhouse effect. Adjust CO₂, CH₄, and N₂O concentrations, albedo, and solar intensity to see equilibrium temperature. View radiative forcing breakdowns, enable water vapor and ice-albedo feedbacks, and project temperature through 2100 under RCP 4.5, RCP 8.5, and Paris 1.5°C scenarios.
Analyze water quality by measuring pH, dissolved oxygen, nitrate, phosphate, turbidity, and temperature. Calculate a Water Quality Index and simulate eutrophication with nutrient loading, algal blooms, and dissolved oxygen crashes.
Explore atmosphere layers, temperature profiles, pressure changes with altitude, temperature inversions, ozone chemistry, and planetary energy balance. Visualize the troposphere through thermosphere.
Compare coal, gas, nuclear, hydro, wind, solar, geothermal, and biomass across CO₂ emissions, capacity factor, land use, and levelized cost. Build custom grid mixes and analyze lifecycle impacts.
Model water budgets, aquifer cross-sections, contaminant plume dispersion, and well drawdown. Explore Darcy's law, SCS curve number infiltration, and Theis pumping equations interactively.
Calculate soil loss with the Universal Soil Loss Equation (USLE). Compare erosion across land uses and see how conservation practices like terracing, contour farming, and cover crops reduce soil loss.
Explore plate boundary types, the rock cycle, radiometric dating with decay curves, and Earth's internal layers. View cross-sections of divergent, convergent, and transform boundaries with seismic velocity profiles.
Explore the carbon, nitrogen, phosphorus, and water cycles with interactive diagrams. Adjust human impact sliders to see how fossil fuels, fertilizers, and deforestation alter reservoir sizes and flux rates.
Compare conventional, organic, IPM, and permaculture farming systems. Analyze tradeoffs between crop yield, soil health, water quality, carbon footprint, and biodiversity with radar charts.
Explore the lunar cycle, eclipse conditions, and seasonal day length. Visualize moon illumination across 8 phases, compute solar and lunar eclipse geometry from node angles, and calculate day length and solar altitude from the sunrise equation.
Three modes: compute angular resolution (Rayleigh criterion), Dawes limit, magnification, focal ratio, true FOV, exit pupil, and limiting magnitude for a single telescope; compare two telescopes side by side; and find optimal eyepieces from a standard set. SVG ray diagram and warning badges for over-magnification.
Explore the water cycle with an animated diagram, predict weather from temperature/humidity/wind/clouds, identify cloud types, and compare seasonal patterns across climates
See how water, wind, ice, and plants reshape the land over time. Compare erosion agents, label 8 landforms, and explore the difference between weathering and erosion
Watch shadows change length and direction as the sun moves across the sky. Compare daylight hours at the equator and mid-latitudes across seasons. Shadow quiz challenges
Learn about weather hazards like storms, floods, and wildfires. Match hazards to safety measures and design shelters to protect against extreme weather.
Match fossils to ancient habitats and discover what Earth looked like millions of years ago. Explore trilobites, ammonites, fern leaves, and more. Compare rock layers to see how environments changed over time.
Explore where all of Earth's water is with interactive pie charts and bar graphs. Learn about saltwater, freshwater, ice caps, groundwater, and why clean water is so precious.
Tap stars to connect constellation lines in an interactive night sky. Rotate through the seasons to see which constellations appear and learn why the sky changes throughout the year.
Sort renewable and nonrenewable resources, practice the Reduce/Reuse/Recycle/Landfill sorting game, and plan a town's energy and water use to protect the environment.
Tap rock layers to discover their age, rock type, and fossils. Arrange layers in order from oldest to newest and reconstruct what events - eruptions, floods, erosion - formed each one.
Classify physical and chemical changes as reversible or irreversible. Sort materials like melting ice, baking bread, and burning wood into the correct category and see evidence for each change.
Explore how waves carry information using a simplified flash code. Learn which wave types (sound, light) can pass through different materials, then encode and decode secret messages.
Discover how gravity and air resistance affect falling speed. Predict which objects fall faster, drop them from a virtual height, and explore why objects fall at the same rate in a vacuum.
Discover why stars look brighter or dimmer based on both their actual luminosity and their distance from Earth. Move a star closer and farther to see how apparent brightness changes.
Classify Earth events as fast (earthquakes, floods) or slow (erosion, canyon formation) changes. Sort events onto a geologic timeline and explore the timescales of Earth processes.
Explore a physical map to identify mountains, valleys, plains, coasts, deltas, canyons, peninsulas, and islands. Match landforms to the processes that formed them.
Explore how volcanic eruptions, droughts, wildfires, and other events cascade across Earth's atmosphere, hydrosphere, geosphere, and biosphere. Grades 4-5.
Observe weather conditions and sort clothing for sunny, rainy, snowy, cloudy, and windy days. Practice matching your outfit to the weather outside. Grades K-1.
Click any point on a 3D globe to dig a tunnel straight through Earth. See the antipode, fall time, Earth layers with temperature and pressure, and the country on the other side.
Click two points on a world map to find the shortest path between them on Earth's surface. See surface distance, chord distance through Earth, and initial bearing.
See the live day and night boundary on a 3D globe. Drag the time slider to explore how axial tilt causes seasons, and click any location to see sunrise and sunset times.
Click any location on Earth to measure local gravitational acceleration. See how gravity varies with latitude and altitude, calculate your weight, and compare with other planets.
Click an epicenter to animate P-waves and S-waves spreading across Earth. Measure arrival times, see the S-wave shadow zone created by Earth's liquid core, and explore the S-P gap.
Calculate how much Earth curves over any distance and whether a distant object is visible above the horizon. See the geometry with an interactive cross-section diagram.
Explore how Earth's rotation creates time zones. Move the sun to any UTC time, click a location to see solar time versus standard time, and discover rotation speed by latitude.
Track the ISS, Starlink constellation, and GPS satellites live on an interactive 3D globe. See real-time altitude, speed, orbital period, and ground track using SGP4 propagation.
Launch a projectile between any two world cities and see the trajectory arc, max altitude, flight time, Coriolis deflection, and gravity variation by latitude.
Explore the Moon's phase, illumination percentage, rise and set times, current altitude, and sky position for any date and location on Earth. Watch the Moon move across the sky throughout the day.
Explore the paths of 38 notable solar eclipses from 1999 to 2045 on an interactive 3D globe. Filter by total, annular, or hybrid type. Click any path to see duration, width, and region details.
Explore how pressure systems drive global wind patterns. Place High and Low pressure centers on a world map, watch animated geostrophic wind particles, toggle jet stream overlays, and see Coriolis-driven cyclone and anticyclone rotation.
Visualize where people live on an interactive world map. Switch overlays to compare population density, elevation zones, climate types, tectonic plates, and GDP per capita across 60 countries.
Explore light pollution and sky darkness worldwide using the Bortle scale. Click locations to see Milky Way visibility, stars visible, and astronomy quality ratings.
Click to place an earthquake epicenter on the world map, then watch tsunami waves radiate outward. See arrival times and wave heights for 20 coastal cities with real ocean physics.
See what's in the sky directly overhead right now — stars, constellations, planets, and the ISS. Uses your location for accurate real-time sky calculations with a live sky dome view.
Click between igneous, sedimentary, and metamorphic rocks to explore how heat, pressure, weathering, and melting transform each rock type into another. Includes real examples and geological process explanations.
Explore convergent, divergent, and transform tectonic plate boundaries with animated cross-section diagrams. See how mountains, trenches, rifts, and strike-slip faults form at each boundary type.
Locate earthquake epicenters using P-wave and S-wave arrival times at three seismograph stations. Adjust P and S arrival times for Alpha, Beta, and Gamma stations; the tool computes the S-P time difference, converts it to distance using wave speeds (P=6.0 km/s, S=3.5 km/s), and triangulates the epicenter via Cramer's rule. Displays station positions and calculated epicenter on a grid map. Six presets including shallow, deep, and offshore events.
Explore 12 major ocean currents on an interactive SVG world map including the Gulf Stream, Kuroshio, Humboldt, and Antarctic Circumpolar currents. Click any current to see its temperature, speed, depth, and ecological significance. Toggle temperature overlay to see warm and cold current patterns, and switch to thermohaline circulation mode to visualize the global ocean conveyor belt.
Model the global carbon cycle with adjustable flux sliders for fossil fuel emissions, deforestation, ocean uptake, and land sink. View a live SVG reservoir diagram showing atmosphere, ocean, biosphere, and geosphere boxes with flow arrows, and a 100-year CO2 projection chart. Five presets: Pre-industrial, Current (2024), 2050 Moderate Policy, 2050 High Emissions, and Net Zero. Includes temperature anomaly calculation and tipping point warnings.
Analyze climate data for 20 preset cities worldwide using Walter-Lieth style climographs with dual-axis temperature and precipitation. Automatically classifies each city's Köppen climate type (Af, BWh, Cfb, Dfb, ET, and more) and displays the biome name and climate group. Compare two cities side by side, and view statistics including annual mean temperature, annual precipitation, temperature range, warmest and coldest months.
Explore topographic maps with an interactive 3D terrain view and corresponding 2D contour map. Choose from five terrain presets: mountain, valley, plateau, coastal, and volcano. The 3D view uses imperative Three.js with vertex-colored heightmap and OrbitControls for rotation and zoom. Click any point on the 2D map to read its elevation. Adjust the contour interval to see more or fewer contour lines.
Compare spiral, barred spiral, elliptical, and irregular galaxies side by side. Click a type to see mass range, age, star-formation rate, and a real-world example.
Compare planet sizes and distances. Toggle scale modes, watch orbits move, click any planet for facts.
Adjust the mass of a black hole and visualize the Schwarzschild radius, photon sphere, ISCO, and gravitational light bending. AP Physics and intro general relativity.
Interactive Earth energy budget with the one-layer Stefan-Boltzmann model. Adjust CO2, albedo, solar irradiance, and effective emissivity to see how greenhouse trapping shifts Earth's surface temperature.
Find the sunrise, sunset, solar noon, day length, and twilight times for any location and date. See how latitude and the seasons change the length of your day, including polar day and night.
See how the Moon and Sun create ocean tides. Explore the two tidal bulges, spring and neap tides, the tidal day, and the semidiurnal, diurnal, and mixed tide patterns.
Identify the main cloud types by altitude and form, from cirrus to cumulonimbus, and learn what weather each one signals.
Learn the air masses and the four front types (cold, warm, stationary, occluded), with cross-sections showing the clouds and weather each front brings.
Adjust recharge and well pumping and watch the water table rise or fall and a cone of depression form. Covers aquifers, the water table, porosity, and permeability.
Sort statements into weather or climate and learn the time-scale clue that tells them apart, plus the factors that shape a region's climate.
Identify common minerals from their properties: Mohs hardness, luster, streak, cleavage, and special tests. Includes the hardness scale with field tests and a full property table.
Travel through Earth's history across eons, eras, and periods with a scaled timeline of major events and life, then place events in the right interval.
Pick a nominal size and an ISO hole-basis fit such as H7/g6, then see the hole and shaft limits, the maximum and minimum clearance, and whether the result is a clearance, transition, or interference fit. Computed from ISO 286 tolerance grades and fundamental deviations.
Practice conjugating Spanish verbs across the present, preterite, imperfect, and future tenses. Includes regular and common irregular verbs, an accent helper, and three difficulty levels.
Learn when to use ser and estar with the color-coded DOCTOR and PLACE categories. Choose the correct form in real sentences and see the rule behind each answer.
Decide between the preterite and imperfect in past-tense sentences. Signal words and rule explanations show why each aspect fits.
Practice noun gender and the right article (el, la, un, una) with the ending rules and common exceptions. Covers singular and plural forms.
Master Spanish stress and written accents with the aguda, llana, and esdrújula rules. Click the stressed syllable or type the accented word.
Study Spanish vocabulary with flippable flashcards across eight themes, plus a typed quiz mode with spaced review.
Arrange Spanish word tiles into correct sentences. Teaches word order, adjective placement, and gender and number agreement.
Master the Spanish interrogatives (qué, quién, cuál, dónde, cuándo, and more), including the written accent and the tricky qué vs cuál contrasts.
Listen to Spanish words and phrases and type what you hear. Uses your device's Spanish voice with normal and slow playback.
Learn everyday classroom Spanish with a matching game and typed recall. Covers greetings, teacher commands, student questions, and courtesy.
Social Studies
New York Regents U.S. History and Government Practice
Original New York Regents history and government practice with attributed sources, context, civic literacy and enduring-issues reasoning; no official score prediction.
New York Regents Global History and Geography II Practice
Original New York Regents history and government practice with attributed sources, context, civic literacy and enduring-issues reasoning; no official score prediction.
Texas STAAR Grade 8 Social Studies Practice
Original Texas social studies practice with historical reasoning, sources, geography, government and economics; no official score prediction.
Texas STAAR U.S. History Practice
Original Texas social studies practice with historical reasoning, sources, geography, government and economics; no official score prediction.
Map Skills Explorer
Practice four map reading skills: cardinal and ordinal compass directions, grid coordinate reading, map symbol identification, and distance scale calculations. Four interactive activities for grades 3-8.
Historical Timeline Maker
Build interactive timelines of historical events by year, category, and description. Color-coded by event type. Three presets: American Revolution, Civil Rights Movement, and Ancient Civilizations.
Branches of Government Explorer
Explore the three branches of US government with an interactive civics tool. Learn Congressional and Presidential powers, how checks and balances work, how a bill becomes law, and test knowledge with a quiz.
Supply and Demand Visualizer
Plot supply and demand curves on an interactive graph and find the equilibrium price and quantity. Explore price floors, price ceilings, market surplus and shortage with three real-world economic scenarios.
Primary vs Secondary Sources
Classify 10 sources as primary or secondary, analyze famous historical documents using the SOAPST framework, and practice generating MLA citations across four guided activities.
Historical Causation Chain Builder
Assign historical events to their causal role, long-term cause, trigger, the event, short-term consequence, and long-term consequence, then see the full cause and effect chain. Practice with World War I, the American Revolution, and the Industrial Revolution.
Voting Systems Explorer
Enter voter blocs with ranked ballots, then run the same votes through plurality, ranked-choice (instant runoff), Borda count, and approval voting. See how the winner can change with the method, with round-by-round runoff and a Condorcet check.
Federal Budget Builder
Allocate federal spending across major categories under a revenue constraint, then see the annual deficit or surplus, the national debt projected over years with compounding net interest, and the debt-to-GDP ratio. Uses illustrative round numbers to teach fiscal tradeoffs.
Map Projection & Distortion Explorer
Switch between Mercator, equal-area, and other map projections and see how flattening a round Earth distorts area, shape, and distance. Includes a graticule, Tissot distortion circles, an area-scale-by-latitude readout, and the classic Greenland vs Africa size illusion.
Types of Government Sorter
Sort real-world scenarios under the correct form of government: democracy, republic, monarchy, dictatorship, oligarchy, theocracy, and more. Reveals a definition and example for each.
Checks and Balances Simulator
See how each branch of the US government checks the others with vetoes, overrides, judicial review, impeachment, and confirmations. Quiz scenarios plus a full checks matrix.
How a Bill Becomes a Law
Move a bill through the US legislative process step by step, from introduction and committee to floor votes, the other chamber, and presidential action with veto and override branches.
Constitutional Amendments Explorer
Browse all 27 amendments to the US Constitution in plain language and quiz yourself on which amendment protects each right, with a focus on the Bill of Rights.
Landmark Supreme Court Cases
Explore the major US Supreme Court cases taught in civics and US history. Each case covers the dispute, the ruling, and the constitutional principle, with a matching quiz.
Electoral College Simulator
Assign each state's electoral votes and watch the tally race to 270. Shows how a candidate can win the presidency without winning the popular vote.
Federalism Powers Sorter
Sort government powers into federal, state, and shared categories. Learn which level of government holds each power and the constitutional basis behind it.
Economic Systems Comparator
Compare traditional, command, market, and mixed economies across who decides, private property, and the role of government, then sort scenarios into the right system.
Citizen Rights and Responsibilities
Sort statements into the rights, legal duties, and civic responsibilities of US citizens. Learn the difference between what is protected, what is required, and what is expected.
Political Spectrum Explorer
Learn the left-right political spectrum neutrally. Place general policy positions along the spectrum and see how views on the economy and society are described.