Science Worksheet: Identifying Variables | PDF - Free Printable

Let’s go through each problem one by one. We’ll figure out the three types of variables:

- Independent variable → What the experimenter changes on purpose.
- Dependent variable → What is measured or observed as a result (it “depends” on the independent variable).
- Control variable → Things that are kept the same so they don’t mess up the experiment.

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Problem 1:
> Two groups of sixth graders were tested to compare their speed in solving long division problems. One group had calculators, the other didn’t.

- What changed? → Whether they used calculators or not → Independent variable
- What was measured? → Speed in solving problems → Dependent variable
- What stayed the same? → Grade level (sixth graders), type of math (long division), test conditions → Control variable

✔ Answer:
- Dependent variable: Speed in solving long division problems
- Independent variable: Use of calculators (yes/no)
- Control variable: Grade level / Type of math problem

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Problem 2:
> Students of different grades were given the same jigsaw puzzle to assemble. The time they took to assemble it was measured.

- What changed? → Grade level of students → Independent variable
- What was measured? → Time to assemble puzzle → Dependent variable
- What stayed the same? → Same puzzle, same instructions, same environment → Control variable

✔ Answer:
- Dependent variable: Time to assemble the puzzle
- Independent variable: Grade level of students
- Control variable: Same jigsaw puzzle

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Problem 3:
> Sasha wanted to figure out what type of liquid worked best for growing beans. She watered one with coca-cola, one with lemonade, and one with just water. After one week, she measured how high they had grown.

- What changed? → Type of liquid used → Independent variable
- What was measured? → Height of bean plants → Dependent variable
- What stayed the same? → Type of plant (beans), amount of liquid?, sunlight?, pot size? → Control variable (we assume these were kept same)

✔ Answer:
- Dependent variable: Height of bean plants after one week
- Independent variable: Type of liquid (coca-cola, lemonade, water)
- Control variable: Type of plant (beans), growing conditions (light, soil, etc.)

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Problem 4:
> Miss Kobayashi wanted to find out what fertilizer works best in growing Marigolds. He put Miracle Grow on the first pot, Scotts Fertilizer on the second, and no fertilizer on the third.

- What changed? → Type of fertilizer (including none) → Independent variable
- What was measured? → How well marigolds grew (height, health, flowers — implied) → Dependent variable
- What stayed the same? → Type of flower (Marigold), pot size, water, light → Control variable

✔ Answer:
- Dependent variable: Growth of Marigold plants
- Independent variable: Type of fertilizer (Miracle Grow, Scotts, none)
- Control variable: Type of plant (Marigold), growing conditions

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Problem 5:
> Luffy wanted to see if eating apples would help him do better on his classwork. Day 1: 0 apples, Day 2: 1 apple, Day 3: 2 apples, Day 4: 3 apples. Each day he recorded his science grades.

- What changed? → Number of apples eaten per day → Independent variable
- What was measured? → Science grades → Dependent variable
- Control variable? → Not asked here, but things like same subject, same teacher, same time of day, sleep, etc. would be controls. But since question only asks for dependent and independent, we skip control.

✔ Answer:
- Dependent variable: Science grades
- Independent variable: Number of apples eaten per day

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Final Answer:

1.
- Dependent variable: Speed in solving long division problems
- Independent variable: Use of calculators
- Control variable: Grade level / Type of math problem

2.
- Dependent variable: Time to assemble the puzzle
- Independent variable: Grade level of students
- Control variable: Same jigsaw puzzle

3.
- Dependent variable: Height of bean plants after one week
- Independent variable: Type of liquid (coca-cola, lemonade, water)
- Control variable: Type of plant (beans), growing conditions

4.
- Dependent variable: Growth of Marigold plants
- Independent variable: Type of fertilizer (Miracle Grow, Scotts, none)
- Control variable: Type of plant (Marigold), growing conditions

5.
- Dependent variable: Science grades
- Independent variable: Number of apples eaten per day