Controlling variables (age 11+)

Question 1

Mia designs an experiment to test how the type of material used for a shoe sole (rubber, foam, or plastic) influences the distance a small toy car rolls down a ramp. She will roll the car from the same spot each time, keep the ramp angle at 30°, use cars that all weigh the same, and make sure the ramp surface is dry. Which of the following correctly lists the independent variable, the dependent variable, and three control variables for Mia’s experiment?

Accepted Answer

Independent variable – type of sole material; Dependent variable – distance the car rolls; Control variables – ramp angle, car weight, ramp surface condition.

Answer

Independent variable – distance the car rolls; Dependent variable – type of sole material; Control variables – ramp angle, car weight, ramp surface condition.

Answer

Independent variable – type of sole material; Dependent variable – distance the car rolls; Control variables – type of car wheels, ramp angle, car weight.

Answer

Independent variable – ramp angle; Dependent variable – distance the car rolls; Control variables – type of sole material, car weight, ramp surface condition.

Question 2

Alex wants to find out how the length of a paper airplane's wingspan (independent variable) affects how far it travels (dependent variable). Which of the following is the best hypothesis for Alex's experiment?

Accepted Answer

I predict that a larger wingspan will increase the distance the airplane flies because a larger wing generates more lift, keeping the plane in the air longer.

Answer

I predict that a larger wingspan will affect the distance the airplane flies.

Answer

I predict that the distance the airplane flies will affect the wingspan because longer flights need longer wings.

Answer

I predict that the airplane will fly farther if I use heavier paper because heavier paper goes faster.

Question 3

Jordan wants to test how the amount of baking soda added to a model volcano influences the height of the eruption. Which investigation plan correctly includes repeated measurements, an appropriate sample size, and identifies hazards with proper safety measures?

Accepted Answer

Use three amounts of baking soda (2 g, 4 g, 6 g). For each amount, carry out six trials, measuring the eruption height each time and later calculating the average. Keep the vinegar volume (50 mL), bottle size, and room temperature constant. Identify the hazards of vinegar splashing and baking‑soda dust; wear goggles and gloves, work on a tray, and perform the experiment in a well‑ventilated area.

Answer

Use three amounts of baking soda (2 g, 4 g, 6 g). For each amount, perform one trial and record the eruption height. Keep the vinegar volume the same. No special safety equipment is needed because the chemicals are harmless.

Answer

Use three amounts of baking soda (2 g, 4 g, 6 g). Perform two trials for each amount and record the heights. The amount of vinegar is changed each time to keep the reaction lively. Wear safety goggles only if the mixture splashes.

Answer

Use three amounts of baking soda (2 g, 4 g, 6 g). Perform six trials for each amount and record the heights. All other materials are left as they are, and no hazards are mentioned because the experiment is done outdoors.

Try three questions

Alex wants to find out how the length of a paper airplane's wingspan (independent variable) affects how far it travels (dependent variable). Which of the following is the best hypothesis for Alex's experiment?

Jordan wants to test how the amount of baking soda added to a model volcano influences the height of the eruption. Which investigation plan correctly includes repeated measurements, an appropriate sample size, and identifies hazards with proper safety measures?

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