Identifying Independent Variables worksheet - Free Printable

Let's solve this step by step. The goal is to identify the independent variable in each scenario.

🔍 What is an Independent Variable?

The independent variable is the factor that is deliberately changed or manipulated by the experimenter to observe its effect on the dependent variable (the outcome being measured).

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Now, let’s go through each scenario:

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1. One chicken is injected with a growth hormone while another chicken is not injected. Both chickens are weighed after a year.

- What is being changed? Whether or not the chicken receives the growth hormone.
- What is being measured? Weight after a year.
- ✔ Independent Variable: *Injection of growth hormone*

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2. A bug repellent is sprayed on one arm; the other arm is not sprayed. The number of bug bites is recorded after 2 hours.

- What is being changed? Whether bug repellent is applied.
- What is being measured? Number of bug bites.
- ✔ Independent Variable: *Application of bug repellent*

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3. Javier sleeps 9 hours the night before his science exam. His twin sister has the same exam and sleeps 6 hours the night before the test. Afterwards, they compare their scores.

- What is being changed? Amount of sleep (9 vs. 6 hours).
- What is being measured? Exam scores.
- ✔ Independent Variable: *Amount of sleep*

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4. Group A exercises for a month. Group B does not exercise. They measure the amount of weight they gained.

- What is being changed? Exercise (yes/no).
- What is being measured? Weight gain.
- ✔ Independent Variable: *Exercise*

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5. One math class studies for an assessment while the math class next door does not. The scores of the two classes are compared.

- What is being changed? Whether the class studies or not.
- What is being measured? Test scores.
- ✔ Independent Variable: *Studying for the assessment*

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6. One plant is given sunlight every day. Another plant is not given any sunlight. After 3 weeks, we measure how tall the plant is.

- What is being changed? Exposure to sunlight (yes/no).
- What is being measured? Plant height.
- ✔ Independent Variable: *Sunlight exposure*

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7. One plant is given sunlight for 12 hours a day. Another plant is not given any sunlight. After 3 weeks, we compare how green each plant looks.

- What is being changed? Amount of sunlight (12 hours vs. none).
- What is being measured? How green the plant looks.
- ✔ Independent Variable: *Amount of sunlight per day*

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✔ Final Answers:

| Scenario | Independent Variable |
|--------|----------------------|
| One chicken is injected... | Injection of growth hormone |
| A bug repellent is sprayed... | Application of bug repellent |
| Javier sleeps 9 hours... | Amount of sleep |
| Group A exercises for a month... | Exercise |
| One math class studies... | Studying for the assessment |
| One plant is given sunlight every day... | Sunlight exposure |
| One plant is given sunlight for 12 hours... | Amount of sunlight per day |

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✔ These are all correctly identified based on what is being deliberately changed in each experiment.