Let's analyze each scenario in the table to identify the
independent variable (the factor that is manipulated or changed by the experimenter) and the
dependent variable (the outcome that is measured or observed).
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🔹 Scenario 1: Cow Growth Hormone
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Description: A cow is given a growth hormone and compared to another cow that was not given it. Both cows were weighed after 2 weeks.
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Independent Variable: Whether the cow received the growth hormone (yes/no).
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Dependent Variable: The weight of the cow after 2 weeks.
✔ Answer:
- Independent:
Growth hormone treatment
- Dependent:
Weight gain
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🔹 Scenario 2: Mosquito Repellent
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Description: One group of mosquitoes is sprayed with repellent, the other is not. Number of mosquitoes bitten is counted after 2 hours.
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Independent Variable: Use of mosquito repellent (sprayed vs. not sprayed).
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Dependent Variable: Number of mosquitoes bitten.
✔ Answer:
- Independent:
Use of mosquito repellent
- Dependent:
Number of mosquitoes bitten
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🔹 Scenario 3: Water Temperature and Plant Growth
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Description: One plant is placed in tap water, another in hot water. Change in plant height is measured after a day.
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Independent Variable: Type of water (tap water vs. hot water).
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Dependent Variable: Change in plant height.
✔ Answer:
- Independent:
Water temperature/type
- Dependent:
Change in plant height
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🔹 Scenario 4: Two Cars Traveling at Different Speeds
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Description: Two cars travel at 60 km/h and 40 km/h from the same point. Time taken to reach a city is measured.
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Independent Variable: Speed of the car (60 km/h vs. 40 km/h).
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Dependent Variable: Time taken to reach the destination.
✔ Answer:
- Independent:
Speed of the car
- Dependent:
Time taken to reach the city
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🔹 Scenario 5: Pillbugs in Humidity
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Description: Pillbugs are placed in a container with a choice between dry and moist environments. Researchers record how much time they spend in each side.
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Independent Variable: Moisture level (dry vs. moist environment).
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Dependent Variable: Amount of time spent in each environment.
✔ Answer:
- Independent:
Humidity level (moist vs. dry)
- Dependent:
Time spent in each area
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🔹 Scenario 6: Stapler Performance
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Description: A stapler is used to staple 100 papers. It jams 5 times during the task. Then a different brand of staples is used, and it jams 22 times.
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Independent Variable: Type of staple (brand).
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Dependent Variable: Number of jams.
✔ Answer:
- Independent:
Type of staple
- Dependent:
Number of jams
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🔹 Scenario 7: Cockroaches Exposed to Pesticide
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Description: Cockroaches are exposed to pesticide for 3 hours. 95% die.
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Independent Variable: Exposure to pesticide (or duration/amount of exposure).
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Dependent Variable: Percentage of cockroaches that died.
✔ Answer:
- Independent:
Pesticide exposure
- Dependent:
Mortality rate (percentage dead)
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✔ Final Table Summary:
| Scenario | Independent Variable | Dependent Variable |
|--------|----------------------|--------------------|
| 1 | Growth hormone treatment | Weight gain |
| 2 | Use of mosquito repellent | Number of mosquitoes bitten |
| 3 | Water type (tap vs. hot) | Change in plant height |
| 4 | Car speed (60 vs. 40 km/h) | Time to reach city |
| 5 | Humidity level (dry vs. moist) | Time spent in each area |
| 6 | Type of staple | Number of jams |
| 7 | Pesticide exposure | Percentage of cockroaches that died |
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📌 Key Concept Recap:
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Independent Variable: What you *change* or manipulate.
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Dependent Variable: What you *measure* or observe as a result.
This helps scientists understand cause-and-effect relationships in experiments.
Parent Tip: Review the logic above to help your child master the concept of independent variable dependent variable worksheet.
