Planning Fair Tests
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3rd Grade Science › Planning Fair Tests
Read about the test students are planning. Carlos will test if higher ramps make a toy car roll farther. He will try ramp heights of 2, 4, 6, 8, and 10 inches. What should students do to make sure the test is fair?
Try each height 3 times, but also change the starting spot and the ramp material to make the test more interesting.
Use the same toy car, the same cardboard ramp, the same starting spot, and the same floor; only change the ramp height and measure from the ramp’s end.
Use a different toy car for each height and start each car from a different place, then measure how far each one rolls.
Keep all ramps the same height, but change the floor surface each time to see which floor makes the car roll farthest.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. For example, if you test ramp heights but also change the car and starting spot, you won't know if distance differences came from height or the other changes. Fair tests help you understand what really causes the results. In this scenario, students want to test if higher ramps make a toy car roll farther. To make it fair, they should keep these variables the same: toy car, ramp material, starting spot, floor surface, measurement point. The ONLY thing they should change is the ramp height. Choice A is correct because it identifies proper controls: Use the same toy car, the same cardboard ramp, the same starting spot, and the same floor; only change the ramp height and measure from the ramp’s end. This makes the test fair because if all other factors stay the same, any difference in results must come from the ramp height being tested. Choice B represents changes multiple variables. Students who choose this may not understand that changing multiple things makes it impossible to know what caused the results. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If [variable X] AND [variable Y] both change, can we tell which one caused the result?" Practice identifying: "We're testing [X], so [X] changes. Everything else must stay the same." Use formula: ONLY change [test variable]; keep [list controls] all the same.
Look at the experiment. Chen and Maya have 6 bean plants. They want to test if plants grow better in sunlight or shade for 2 weeks. Which variable should students change to test this question?
Change the plant type for each pot, using beans, peas, and flowers, and then compare which type grows tallest after 2 weeks.
Change the amount of water each day for different plants, and also use different pot sizes, then compare the growth after 2 weeks.
Change where the plants are placed: 3 in a sunny window and 3 in a shady corner, while keeping pot size, soil, water, and start day the same.
Change how tall the plants are by trimming some leaves, then see which plants are taller at the end of 2 weeks.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. For example, if you test plant growth in sun versus shade but also change pot size and water amount, you won't know if growth differences came from light or the other changes. Fair tests help you understand what really causes the results. In this scenario, students want to test if plants grow better in sunlight or shade. To make it fair, they should keep these variables the same: plant type, pot size, soil, water amount, start day. The ONLY thing they should change is the location (sunny or shady). Choice C is correct because it identifies proper test variable: Change where the plants are placed: 3 in a sunny window and 3 in a shady corner, while keeping pot size, soil, water, and start day the same. This makes the test fair because keeping these variables constant means only the light affects growth, making results reliable. Choice B represents changes multiple variables. Students who choose this may not understand that changing multiple things makes it impossible to know what caused the results. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If [variable X] AND [variable Y] both change, can we tell which one caused the result?" Practice identifying: "We're testing [X], so [X] changes. Everything else must stay the same." Use formula: ONLY change [test variable]; keep [list controls] all the same.
Read about the test students are planning. Jamal has 3 magnets and wants to see which is strongest by counting paper clips. To make it a fair test, what should he keep the same?
Keep the paper clips the same size, pick them from the same container, hold each magnet the same distance above the clips, and count clips in a hanging chain.
Keep the number of paper clips different for each magnet, and hold each magnet at a different height to make sure every magnet gets a chance.
Keep the magnet type the same, but change the paper clip size each time to see which magnet works best with different kinds of clips.
Keep everything the same so the test is fair, and then choose the magnet that looks like it can hold the most paper clips.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. In this scenario, students want to test which magnet is strongest by counting paper clips. To make it fair, they should keep these variables the same: paper clip size, same container, same distance above clips, and same counting method. The ONLY thing they should change is which magnet they use. Choice B is correct because it identifies proper controls: keeping paper clips the same size, picking from the same container, holding each magnet the same distance, and counting clips in a hanging chain. This makes the test fair because if all other factors stay the same, any difference in the number of clips must come from the magnet strength being tested. Choice A represents keeping test variable same. Students who choose this may confuse what should change with what should stay same. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If magnet type AND paper clip size both change, can we tell which one caused the result?" Practice identifying: "We're testing magnet strength, so magnet type changes. Everything else must stay the same." Use formula: ONLY change magnet type; keep paper clips, distance, container, and counting method all the same.
Read about the test students are planning. Amir will test if bigger parachutes fall slower than small ones. He will drop them from 6 feet with a clay ball. To make this a fair test, what should students keep the same?
Keep the shape square, use the same plastic bag material, keep strings 10 inches long, use the same clay ball, and drop from 6 feet; only change parachute size.
Drop each parachute from a different height and use different weights, then compare which parachute falls slowest by watching with your eyes.
Keep the parachute size the same, but change the plastic material and the string length each time, then time how long it takes to fall.
Keep everything the same, including parachute size, and drop all parachutes once to see if the results match.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. For example, if you test parachute sizes but also change materials and drop heights, you won't know if falling speed differences came from size or the other changes. Fair tests help you understand what really causes the results. In this scenario, students want to test if bigger parachutes fall slower. To make it fair, they should keep these variables the same: shape, plastic material, string length, weight (clay ball), drop height. The ONLY thing they should change is the parachute size. Choice B is correct because it identifies proper controls: Keep the shape square, use the same plastic bag material, keep strings 10 inches long, use the same clay ball, and drop from 6 feet; only change parachute size. This makes the test fair because if all other factors stay the same, any difference in results must come from the size being tested. Choice A represents changes multiple variables. Students who choose this may not understand that changing multiple things makes it impossible to know what caused the results. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If [variable X] AND [variable Y] both change, can we tell which one caused the result?" Practice identifying: "We're testing [X], so [X] changes. Everything else must stay the same." Use formula: ONLY change [test variable]; keep [list controls] all the same.
Look at the experiment. Keisha’s group will test which wrap keeps ice frozen longest: newspaper, bubble wrap, or aluminum foil. Each cup gets 4 ice cubes and 2 layers of wrap. Which describes a fair test plan?
Wrap each cup in any amount of material you want, keep them in different rooms, and then guess which wrap works best without timing.
Use different size cups for each wrap and put some cups in the sun and some in the shade, then see which one melts last.
Use the same size cups, 4 ice cubes each, 2 layers of wrap, and keep all cups in the same room; only change the wrapping material and time the melting.
Keep the wrapping material the same for all cups, but change the number of ice cubes in each cup to see which stays frozen longest.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. For example, if you test wrapping materials but also change cup sizes and locations, you won't know if melting differences came from the material or the other changes. Fair tests help you understand what really causes the results. In this scenario, students want to test which wrapping material keeps ice frozen longest. To make it fair, they should keep these variables the same: cup size, number of ice cubes, layers of wrap, room location. The ONLY thing they should change is the wrapping material. Choice A is correct because it identifies proper controls: Use the same size cups, 4 ice cubes each, 2 layers of wrap, and keep all cups in the same room; only change the wrapping material and time the melting. This makes the test fair because if all other factors stay the same, any difference in results must come from the material being tested. Choice B represents changes multiple variables. Students who choose this may not understand that changing multiple things makes it impossible to know what caused the results. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If [variable X] AND [variable Y] both change, can we tell which one caused the result?" Practice identifying: "We're testing [X], so [X] changes. Everything else must stay the same." Use formula: ONLY change [test variable]; keep [list controls] all the same.
Read about the test students are planning. Emma tests 3 paper airplane designs and measures distance to the nose. Why is it important to throw from the same 6-foot height each time?
Because higher throws always make every airplane go the same distance, so height does not matter in any flight test.
Because measuring to the nose is not needed if you throw from 6 feet, since you can just watch which one lands farthest.
Because the height is the only thing you should change when comparing airplane designs, not the design of the plane.
Because changing height could change distance, and then you would not know if the design or the height caused the results.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. In this scenario, students want to test paper airplane designs for distance. To make it fair, they should keep these variables the same: throwing height (6 feet), throwing force, location, and measurement method. The ONLY thing they should change is the airplane design. Choice A is correct because it explains why height must be controlled: changing height could change distance, and then you would not know if the design or the height caused the results. This makes the test fair because keeping throwing height constant means only the airplane design affects distance, making results reliable. Choice C represents misunderstanding of test variable. Students who choose this may confuse what should change with what should stay same or think height is the variable being tested rather than airplane design. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If airplane design AND throwing height both change, can we tell which one caused the result?" Practice identifying: "We're testing airplane design, so airplane design changes. Everything else must stay the same." Use formula: ONLY change airplane design; keep height, force, location, and measurement all the same.
Read about the test students are planning. Sofia will test 3 paper airplane designs to see which flies farthest. Which test plan is fair?
Make all three planes the same design, and change the throwing force to see which one goes farthest.
Test each plane outside on windy days, because real airplanes fly in the wind too.
Throw each plane from different heights, because higher throws help the best plane go the farthest.
Use the same thrower, throw from 6 feet with the same force in the gym, measure to the nose, and only change the plane design.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. In this scenario, Sofia wants to test which paper airplane design flies farthest. To make it fair, she should keep these variables the same: same thrower, throw from 6 feet height, same throwing force, test in the gym (no wind), and measure to the nose. The ONLY thing she should change is the airplane design. Choice C is correct because it identifies proper controls: using the same thrower, height, force, location, and measurement method. This makes the test fair because if all other factors stay the same, any difference in distance must come from the airplane design being tested. Choice A represents changes multiple variables. Students who choose this may think higher throws help show which plane is best, not understanding that changing throw height makes it impossible to know if distance came from height or design. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If airplane design AND throw height both change, can we tell which one caused the result?" Practice identifying: "We're testing airplane design, so design changes. Everything else must stay the same." Use formula: ONLY change airplane design; keep thrower, height, force, location, and measurement all the same.
Read about the test students are planning. Carlos will roll the same toy car down a ramp. Which describes a fair test of ramp height and distance?
Use the same car, same cardboard ramp, same starting spot, and same floor; only change the ramp height and measure from the ramp end each time.
Change the ramp height and also switch to a different toy car for each height to make the test more interesting.
Make it fair by doing 3 trials, even if the floor surface and ramp material change each time.
Keep the ramp height the same every time, and change the starting spot to see what makes the car roll farther.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. In this scenario, Carlos wants to test how ramp height affects rolling distance. To make it fair, he should keep these variables the same: same car, same cardboard ramp material, same starting spot, same floor surface, and measure from the ramp end. The ONLY thing he should change is the ramp height. Choice A is correct because it identifies proper controls: using the same car, ramp material, starting spot, floor, and measurement point. This makes the test fair because if all other factors stay the same, any difference in rolling distance must come from the ramp height being tested. Choice B represents changes multiple variables. Students who choose this may think different cars make the test more interesting, not understanding that changing both height and car makes it impossible to know which factor caused the distance differences. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If ramp height AND car type both change, can we tell which one caused the result?" Practice identifying: "We're testing ramp height, so height changes. Everything else must stay the same." Use formula: ONLY change ramp height; keep car, ramp material, start spot, floor, and measurement point all the same.
Read about the test students are planning. Jamal made 3 paper airplane designs and wants to see which flies farthest in the gym. To make it a fair test, what should he keep the same?
Change the plane design and also throw one outside and one inside to see which one flies farthest.
Use the same plane design each time, but throw from 4 feet, 6 feet, and 8 feet to see which height makes it fly farthest.
Throw all planes from 6 feet high, with the same force, in the gym with no wind, and measure to the nose of the plane; ONLY change the plane design.
Keep things the same and throw each plane 3 times to make the test fair.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. In this scenario, students want to test which paper airplane design flies farthest. To make it fair, they should keep these variables the same: throwing height (6 feet), throwing force, location (gym with no wind), and measurement method (to the nose). The ONLY thing they should change is the airplane design. Choice A is correct because it identifies proper controls: same height, same force, same location, same measurement point, and only changes the plane design. This makes the test fair because if all other factors stay the same, any difference in flight distance must come from the design being tested. Choice B represents keeping test variable same - students who choose this may confuse what should change (design) with what should stay same (height). To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" and multiple items (3-5) under "what stays same." Ask: "If height AND design both change, can we tell which one caused the result?" Practice identifying: "We're testing airplane design, so design changes. Everything else must stay the same." Use formula: ONLY change airplane design; keep height, force, location, and measurement all the same.
Read about the experiment. Keisha is testing 3 magnets by counting paper clips picked up. Why is it important to use the same paper clips each time?
So the results are fair, because different clip sizes could change how many clips a magnet can hold.
So the magnet color matches the paper clips, which helps the magnet work better.
So each magnet can be tested in a different room without affecting the results.
So the strongest magnet gets fewer clips, making the test more challenging.
Explanation
This question tests planning fair tests with controlled variables (NGSS 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved). A fair test means changing only ONE thing (the test variable) while keeping everything else the same (control variables). If you change multiple things at once, you can't tell which change caused the results. In this scenario, students are testing magnet strength by counting paper clips picked up. To make it fair, they should keep these variables the same: paper clip size, paper clip material, testing method, and distance from magnet. The ONLY thing they should change is which magnet is being tested. Choice B is correct because it explains why using same paper clips matters: different clip sizes could change how many clips a magnet can hold. This makes the test fair because if clip sizes varied, you couldn't tell if differences came from magnet strength or clip size. Choice A represents a misconception about color matching. Students who choose this may think matching colors helps magnets work better, not understanding that color doesn't affect magnetic force and that using different clips would make results unreliable. To help students: Create T-chart labeled "What Changes (Test Variable)" and "What Stays Same (Control Variables)." There should be only ONE item under "what changes" (which magnet) and multiple items (3-5) under "what stays same" (clip size, clip material, testing method). Ask: "If magnet AND clip size both change, can we tell which one caused different results?" Practice identifying: "We're testing magnet strength, so magnet changes. Everything else must stay the same." Use formula: ONLY change which magnet; keep paper clips, method, and distance all the same.