Science: Open-Ended CER Writing from Lab Data
Using evidence and reasoning to explain lab results
Science: Open-Ended CER Writing from Lab Data
Using evidence and reasoning to explain lab results
Science - Grade 6-8
- 1
A student tested how the amount of sunlight affects bean plant growth. Four plants were grown for 14 days with different amounts of sunlight each day. Sunlight per day: 2 hours, 4 hours, 6 hours, 8 hours Average plant height after 14 days: 5 cm, 9 cm, 13 cm, 16 cm Write a CER response explaining how sunlight affected plant growth.
Use at least two numbers from the data as evidence.
A strong response should claim that more daily sunlight increased bean plant growth. Evidence includes that plants receiving 2 hours of sunlight grew to 5 cm, while plants receiving 8 hours grew to 16 cm. The reasoning should explain that plants use light energy for photosynthesis, which helps them make food for growth, so plants with more light had more energy available to grow taller. - 2
A class investigated whether water temperature affects how fast sugar dissolves. They added the same amount of sugar to 100 mL of water at different temperatures and stirred at the same speed. Water temperature: 10°C, 25°C, 40°C, 60°C Time to dissolve sugar: 95 s, 62 s, 38 s, 21 s Write a CER response explaining the relationship between temperature and dissolving time.
A strong response should claim that sugar dissolved faster in warmer water. Evidence includes that sugar took 95 seconds to dissolve at 10°C but only 21 seconds at 60°C. The reasoning should explain that warmer water particles move faster and collide more often with sugar particles, causing the sugar to break apart and mix into the water more quickly. - 3
Students measured the bounce height of a rubber ball dropped from different heights. The same ball was used each time. Drop height: 50 cm, 100 cm, 150 cm, 200 cm Bounce height: 32 cm, 65 cm, 97 cm, 129 cm Write a CER response explaining how drop height affected bounce height.
Connect height to energy in your reasoning.
A strong response should claim that a greater drop height caused a greater bounce height. Evidence includes that a ball dropped from 50 cm bounced 32 cm, while a ball dropped from 200 cm bounced 129 cm. The reasoning should explain that dropping the ball from a greater height gives it more gravitational potential energy, which changes into kinetic energy as it falls and then into elastic energy during the bounce. - 4
A student tested which material is the best insulator for keeping water warm. Four identical cups were wrapped in different materials. Each cup started with water at 80°C. The temperature was recorded after 20 minutes. Material: no wrap, paper towel, cotton cloth, aluminum foil Temperature after 20 minutes: 48°C, 55°C, 61°C, 53°C Write a CER response identifying the best insulator in this test.
A strong response should claim that cotton cloth was the best insulator in this test. Evidence includes that the cup wrapped in cotton cloth had water at 61°C after 20 minutes, which was warmer than paper towel at 55°C, aluminum foil at 53°C, and no wrap at 48°C. The reasoning should explain that a good insulator slows the transfer of thermal energy from the hot water to the cooler surroundings, so the water stays warmer for longer. - 5
A group tested how fertilizer affects radish plant growth. They used the same type of soil, light, water, and seeds for all groups. Fertilizer amount: 0 g, 2 g, 4 g, 8 g Average plant height after 21 days: 7 cm, 11 cm, 15 cm, 12 cm Write a CER response explaining what the data show about fertilizer amount and plant growth.
Notice that the largest fertilizer amount did not give the largest plant height.
A strong response should claim that some fertilizer improved plant growth, but too much fertilizer did not produce the tallest plants. Evidence includes that plants with 4 g of fertilizer grew to 15 cm, which was taller than plants with 0 g at 7 cm and 2 g at 11 cm. However, plants with 8 g grew only 12 cm. The reasoning should explain that plants need nutrients to grow, but too much fertilizer can stress plants or harm roots, so an amount near 4 g worked best in this test. - 6
Students tested four mystery liquids with red and blue litmus paper. Red litmus turns blue in a base. Blue litmus turns red in an acid. Liquid A: red litmus stayed red, blue litmus turned red Liquid B: red litmus turned blue, blue litmus stayed blue Liquid C: red litmus stayed red, blue litmus stayed blue Liquid D: red litmus turned blue, blue litmus stayed blue Write a CER response identifying which liquids are acids, bases, or neutral.
A strong response should claim that Liquid A is an acid, Liquids B and D are bases, and Liquid C is neutral. Evidence includes that Liquid A turned blue litmus red, which indicates an acid. Liquids B and D turned red litmus blue, which indicates bases. Liquid C did not change either type of litmus paper. The reasoning should explain that litmus paper changes color based on whether a solution is acidic, basic, or neutral. - 7
A student investigated how surface type affects the distance a toy car travels after rolling down the same ramp. Surface: smooth tile, cardboard, carpet, sandpaper Distance traveled: 240 cm, 180 cm, 95 cm, 60 cm Write a CER response explaining how surface type affected the toy car's motion.
Use the word friction in your reasoning.
A strong response should claim that rougher surfaces reduced the distance the toy car traveled. Evidence includes that the car traveled 240 cm on smooth tile but only 60 cm on sandpaper and 95 cm on carpet. The reasoning should explain that rough surfaces create more friction, and friction is a force that opposes motion, so the car slows down faster and travels a shorter distance. - 8
Students measured how much a spring stretched when different masses were attached. Mass attached: 50 g, 100 g, 150 g, 200 g Spring stretch: 2 cm, 4 cm, 6 cm, 8 cm Write a CER response explaining the pattern between mass and spring stretch.
A strong response should claim that increasing the mass caused the spring to stretch more. Evidence includes that 50 g stretched the spring 2 cm, while 200 g stretched it 8 cm. The data show a steady pattern in which each additional 50 g increased the stretch by 2 cm. The reasoning should explain that greater mass has greater weight, which pulls down on the spring with more force and stretches it farther. - 9
A class tested how the shape of a paper airplane affects flight distance. Each design was thrown by the same person with the same throwing motion. Design: wide wings, narrow wings, short body, long body Average flight distance: 6.2 m, 8.5 m, 5.7 m, 7.9 m Write a CER response identifying which design flew farthest and why the evidence supports that claim.
Compare the winning design to at least two other designs.
A strong response should claim that the narrow-wing paper airplane flew farthest. Evidence includes that the narrow-wing design traveled an average of 8.5 m, which was farther than the long-body design at 7.9 m, the wide-wing design at 6.2 m, and the short-body design at 5.7 m. The reasoning should explain that airplane shape can affect air resistance and lift, and in this test the narrow-wing design may have reduced drag enough to travel the greatest distance. - 10
Students placed identical ice cubes on different colored paper in sunlight and measured how long each ice cube took to melt. Paper color: white, yellow, blue, black Melting time: 18 min, 16 min, 12 min, 8 min Write a CER response explaining how paper color affected melting time.
A strong response should claim that darker paper caused ice to melt faster. Evidence includes that ice on black paper melted in 8 minutes, while ice on white paper melted in 18 minutes. Ice on blue paper melted in 12 minutes, which was also faster than white or yellow paper. The reasoning should explain that darker colors absorb more light energy and change it into thermal energy, which warms the ice and makes it melt more quickly. - 11
A student tested the effect of salt on the freezing point of water. Four cups had the same amount of water but different amounts of salt mixed in. The freezing temperature was recorded. Salt added: 0 tsp, 1 tsp, 2 tsp, 3 tsp Freezing temperature: 0°C, -2°C, -5°C, -7°C Write a CER response explaining how salt affected the freezing point of water.
Explain what happens to the freezing temperature as salt increases.
A strong response should claim that adding more salt lowered the freezing point of water. Evidence includes that water with 0 teaspoons of salt froze at 0°C, while water with 3 teaspoons of salt froze at -7°C. The reasoning should explain that dissolved salt particles interfere with water particles forming solid ice, so the water must become colder before it freezes. - 12
Students investigated how exercise affects heart rate. One student measured their pulse before exercise and after jogging for different lengths of time. Condition: resting, 1 min jogging, 3 min jogging, 5 min jogging Heart rate: 72 bpm, 96 bpm, 124 bpm, 148 bpm Write a CER response explaining how exercise time affected heart rate.
A strong response should claim that longer exercise time increased heart rate. Evidence includes that the resting heart rate was 72 bpm, after 1 minute of jogging it was 96 bpm, and after 5 minutes it was 148 bpm. The reasoning should explain that muscles need more oxygen and energy during exercise, so the heart beats faster to pump more oxygen-rich blood to the muscles. - 13
A group studied how soil type affects how much water drains through it in 5 minutes. Each cup had the same amount of soil and received 100 mL of water. Soil type: sand, garden soil, clay, gravel Water drained: 86 mL, 54 mL, 18 mL, 92 mL Write a CER response explaining which soil allowed the most drainage and which held the most water.
Less water drained means more water was held in the soil.
A strong response should claim that gravel allowed the most water to drain and clay held the most water. Evidence includes that gravel drained 92 mL, which was the highest amount, while clay drained only 18 mL, which was the lowest amount. The reasoning should explain that large spaces between gravel particles let water pass through quickly, while tiny spaces in clay slow water movement and hold more water. - 14
Students tested how the number of wire coils affects the strength of an electromagnet. They wrapped insulated wire around an iron nail and counted how many paper clips it picked up. Number of coils: 10, 20, 30, 40 Paper clips picked up: 4, 9, 15, 21 Write a CER response explaining how the number of coils affected electromagnet strength.
A strong response should claim that increasing the number of wire coils made the electromagnet stronger. Evidence includes that 10 coils picked up 4 paper clips, while 40 coils picked up 21 paper clips. The reasoning should explain that more coils of wire around the nail strengthen the magnetic field produced by the electric current, so the electromagnet can attract more paper clips. - 15
A class collected data on how beak shape affects the ability to pick up different foods. Each tool represented a bird beak. Students counted how many beans each tool could pick up in 30 seconds. Beak tool: spoon, tweezers, clothespin, chopsticks Beans picked up: 28, 18, 12, 9 Write a CER response explaining which beak shape was best for picking up beans and how this relates to adaptation.
Connect the tool's shape to how well it collected the food.
A strong response should claim that the spoon was the best beak shape for picking up beans in this investigation. Evidence includes that the spoon picked up 28 beans in 30 seconds, which was more than tweezers at 18, a clothespin at 12, and chopsticks at 9. The reasoning should explain that structures that help an organism get food can be adaptations, and a beak shape that works well for a certain food source can help a bird survive in its environment.