CSTA K–12 Computer Science Standards
Tools and labs aligned to the Computer Science Teachers Association K–12 standards, covering algorithms, data, networks, and programming from Kindergarten through AP CS.
K–2 Algorithms & Devices
Sequences, patterns, and how devices communicate — for the youngest computer scientists.
Tools
How Messages Travel on the Internet
Watch a message split into numbered packets, travel through routers, and reassemble at the destination. Break a router and see packets reroute.
Waves & Secret Messages
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.
Positional Words & Map Directions Explorer
Practice above, below, beside, between, left, and right using an animal grid map. Answer positional questions to build spatial vocabulary. Grades K-1.
Labs
Shape Sorter & Compose Shapes Lab
Classify 2D shapes by attributes and combine small shapes to build larger ones. Investigate how sides and corners relate, and how simple shapes compose into complex ones. Grades K-1.
Ten-Frame & Subitizing Lab
Investigate how different arrangements on a ten-frame change how quickly you recognize a number. Record data and find the patterns that help you subitize faster. Grades K-1.
Weather Watcher & Clothing Lab
Test outfits against sunny, rainy, snowy, cloudy, and windy weather. Record correct, missed, and wrong choices to find which clothes work in which weather. Grades K-1.
3–5 Data & Problem Solving
Binary numbers, logic, data representation, and introductory algorithms.
Tools
Binary, Decimal & Hex Converter
Convert between binary, decimal, hexadecimal, and octal. Bit-level visualization, ASCII lookup, and step-by-step conversion methods.
Logic Gate Circuit Simulator
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.
Data Compression & Image Encoding Explorer
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.
Internet Routing & Packets Explorer
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.
Labs
Number Systems & Data Representation Lab
Convert between binary, octal, decimal, and hex with step-by-step breakdowns. Explore two's complement signed integers, bitwise operations, and IEEE 754 floating-point representation
Debugging & Unit Testing Lab
Hunt bugs in code snippets, design test cases to catch defects, and classify error types. Track accuracy across difficulty levels and learn systematic debugging strategies
Loops, Debugging & Animation Lab
Compare flat programs to loop-based ones, fix buggy programs, and create event-driven sprite animations
How Messages Travel on the Internet Lab
Split a message into packets, route them through routers step by step, and reassemble them at the destination. Grades 2–5.
6–8 Networks, Programming & Impacts
Sorting algorithms, pathfinding, data structures, cryptography, and the social impacts of computing.
Tools
Sorting Algorithm Visualizer
Watch bubble, selection, insertion, merge, and quick sort in action with color-coded bars for comparisons, swaps, and sorted elements.
Pathfinding Algorithm Visualizer
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.
Data Structure Visualizer
Visualize stacks, queues, linked lists, binary search trees, and min heaps with animated operations. Push, pop, insert, delete, and traverse step by step.
Big-O Complexity Visualizer
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.
Cryptography Explorer
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.
Labs
Searching & Sorting Performance Lab
Compare linear search, binary search, selection sort, insertion sort, and merge sort side by side. Animate comparisons and swaps step by step, collect performance data across array sizes, and verify O(n), O(n log n), and O(n²) complexity
Pathfinding & Heuristic Search Lab
Compare BFS, DFS, Dijkstra, and A* on interactive grids. Explore how heuristic choice affects search efficiency, generate mazes with different algorithms, and record path metrics
Data Structures & Tree Traversal Lab
Explore stacks, queues, linked lists, and binary search trees with visual operations. Perform and compare inorder, preorder, postorder, and level-order traversals. Benchmark structure performance
Selection & Iteration Code Tracing Lab
Step through Java code line by line with variable trace tables. Practice if/else selection, for loops, while loops, nested loops, and AP CSA-style code tracing with predict mode
Cybersecurity Lab
Crack ciphers by brute force, measure password entropy, and explore the avalanche effect in hash functions. Collect data on how key length affects encryption security
9–12 AP CS Principles & AP CS A
Programming paradigms, data analysis, recursion, object-oriented design, and systems thinking.
Tools
Java Array & ArrayList Explorer
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.
Java Strings & Methods Explorer
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.
Class Design & Object Reference Explorer
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.
Recursion & Call Stack Visualizer
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.
Internet Routing & Packets Explorer
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.
Data Compression & Image Encoding Explorer
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.
Labs
Java Strings Lab
Explore Java String methods like substring, indexOf, compareTo, and charAt with a character-index grid. Trace through string algorithms including reverse, palindrome check, and Caesar cipher
Network Reliability & Fault Tolerance Lab
Test network redundancy by disabling nodes and links. Measure packet delivery rates, latency, and independent paths across star, ring, mesh, and tree topologies
Cybersecurity Lab
Crack ciphers by brute force, measure password entropy, and explore the avalanche effect in hash functions. Collect data on how key length affects encryption security
Loops, Debugging & Animation Lab
Compare flat programs to loop-based ones, fix buggy programs, and create event-driven sprite animations
Compression & Information Theory Lab
Encode text with Run-Length Encoding and Huffman coding. Build Huffman trees and compare compression ratios. Calculate Shannon entropy as the theoretical compression limit