Students can use this worksheet to practice identifying independent, dependent, and controlled variables within four different testable scientific questions.

To solve this problem, we need to identify the independent, dependent, and controlled variables in each testable question. Let’s go step by step for each one:

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1) Will using liquid fertilizer make grass grow greener than granulated fertilizer?

- Independent Variable: This is what you change on purpose. Here, it’s the *type of fertilizer* (liquid vs. granulated).
- Dependent Variable: This is what you measure or observe as a result. Here, it’s how *green the grass grows*.
- Controlled Variables: These are things you keep the same so they don’t affect the outcome. Examples: amount of water, sunlight, type of grass, soil, temperature, etc.

✔ So:
- Independent: Type of fertilizer
- Dependent: How green the grass gets
- Controlled: Water, sunlight, grass type, soil, etc.

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2) Does changing the wing shape to make it more narrow affect the distance a paper airplane will fly?

- Independent Variable: What you’re changing — here, it’s the *wing shape* (narrower vs. not).
- Dependent Variable: What you’re measuring — the *distance the plane flies*.
- Controlled Variables: Things kept constant — like the paper type, thrower, force of throw, indoor/outdoor setting, etc.

✔ So:
- Independent: Wing shape
- Dependent: Distance flown
- Controlled: Paper type, throwing force, environment, etc.

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3) How does heat affect the motion of water molecules?

- Independent Variable: What you’re changing — *heat level* (e.g., cold, warm, hot water).
- Dependent Variable: What you’re observing — *motion of water molecules* (faster when heated).
- Controlled Variables: Amount of water, container type, starting temperature, measurement method, etc.

✔ So:
- Independent: Heat level
- Dependent: Motion of water molecules
- Controlled: Water amount, container, initial temp, etc.

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4) How does watching TV during studying affect a student’s test grades?

- Independent Variable: What you’re changing — *whether or not TV is watched while studying*.
- Dependent Variable: What you’re measuring — *test grades*.
- Controlled Variables: Study time, subject being studied, test difficulty, sleep before test, distractions other than TV, etc.

✔ So:
- Independent: Watching TV during study
- Dependent: Test grades
- Controlled: Study time, subject, test difficulty, sleep, etc.

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Final Answer:
1) Independent: Type of fertilizer; Dependent: Grass color/greenness; Controlled: Water, sunlight, grass type, soil
2) Independent: Wing shape; Dependent: Flight distance; Controlled: Paper type, throw force, environment
3) Independent: Heat level; Dependent: Molecular motion; Controlled: Water amount, container, initial temp
4) Independent: TV watching during study; Dependent: Test grades; Controlled: Study time, subject, test difficulty, sleep