Identifying Independent Variables worksheet - Free Printable

You're asked 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).

---

Let’s go through each scenario one by one:

---

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 gets the growth hormone injection.
- Independent Variable: Presence or absence of growth hormone injection

---

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? → Which arm gets the bug repellent.
- Independent Variable: Application of bug repellent (sprayed vs. not sprayed)

---

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

- What is being changed? → Amount of sleep before the exam.
- Independent Variable: Hours of sleep before the exam

*(Note: This is a natural experiment — they didn’t randomly assign sleep, but since we’re identifying what’s being compared as the cause, sleep duration is still the independent variable.)*

---

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

- What is being changed? → Whether or not they exercise.
- Independent Variable: Exercise (exercising vs. not exercising)

---

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 for the assessment.
- Independent Variable: Studying for the assessment (studying vs. not studying)

---

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.
- Independent Variable: Exposure to sunlight (sunlight vs. no sunlight)

---

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 exposure (12 hours vs. 0 hours).
- Independent Variable: Duration of sunlight exposure per day

*(Even though both groups differ in sunlight, the key manipulation here is the *amount* of sunlight — 12 hours vs. none. So it’s the duration of exposure.)*

---

## ✔ Final Answers (to fill in the table):

| Scenario | Independent Variable |
|----------|----------------------|
| 1. Chicken injected with growth hormone vs. not | Growth hormone injection (yes/no) |
| 2. Bug repellent sprayed on one arm, not the other | Application of bug repellent |
| 3. Javier sleeps 9 hrs, sister sleeps 6 hrs | Hours of sleep before exam |
| 4. Group A exercises, Group B does not | Exercise (yes/no) |
| 5. One class studies, other does not | Studying for assessment (yes/no) |
| 6. One plant gets sunlight daily, other gets none | Sunlight exposure (yes/no) |
| 7. One plant gets 12 hrs sun/day, other gets none | Duration of sunlight exposure per day |

---

✔ You can now fill in the “Independent Variable” column in your worksheet with these answers!

Let me know if you’d like help identifying the *dependent variables* too!