Engaging Science Variables Worksheet for Students - Free Printable

To solve this worksheet, we need to identify three types of variables for each experiment:

- Independent Variable: This is what the scientist *changes* or *controls* on purpose to test.
- Dependent Variable: This is what is *measured* or *observed* — it depends on the independent variable.
- Control Variable: These are things that are *kept the same* so they don’t affect the results.

Let’s go through each problem one by one.

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Problem 1:
> Different rose bushes are grown in a greenhouse for two months. The number of flowers on each bush is counted at the end of the experiment.

- What’s being changed? → Different types of rose bushes.
- What’s being measured? → Number of flowers.
- What’s kept the same? → Greenhouse, time (two months), care conditions (implied).

✔ So:
a. Independent Variable: Type of rose bush
b. Dependent Variable: Number of flowers
c. Control Variable: Greenhouse environment, duration (2 months)

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Problem 2:
> You water three sunflower plants with salt water. Each plant receives a different concentration of salt solutions. A fourth plant receives pure water. After a two-week period, the height is measured.

- What’s being changed? → Concentration of salt in water (including pure water as control group).
- What’s being measured? → Height of plants.
- What’s kept the same? → Type of plant (sunflower), time (2 weeks), watering method, etc.

✔ So:
a. Independent Variable: Concentration of salt in water
b. Dependent Variable: Height of sunflower plants
c. Control Variable: Type of plant, time period, watering schedule

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Problem 3:
> Three redwood trees are kept at different humidity levels inside a greenhouse for 12 weeks. One tree is left outside in normal conditions. Height of the tree is measured once a week.

- What’s being changed? → Humidity levels (inside greenhouse) and location (one outside).
- What’s being measured? → Height of trees.
- What’s kept the same? → Type of tree (redwood), measurement frequency, time (12 weeks).

Note: The “one tree outside” is actually part of the independent variable — it’s a different condition being tested. But since the question says “different humidity levels inside” and then adds “one outside,” we can consider the independent variable as “humidity level/location.”

✔ So:
a. Independent Variable: Humidity level (or location/environment)
b. Dependent Variable: Height of redwood trees
c. Control Variable: Tree type (redwood), measurement schedule, duration (12 weeks)

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Problem 4:
> Pea plant clones are given different amounts of water for a three-week period. First pea plant receives 400 milliliters a day. Second gets 200 mL/day. Third gets 100 mL/day. Fourth gets no extra water (only natural water). Height is recorded daily.

- What’s being changed? → Amount of water given each day.
- What’s being measured? → Height of pea plants.
- What’s kept the same? → Type of plant (clones = genetically identical), time (3 weeks), measurement frequency.

✔ So:
a. Independent Variable: Amount of water given per day
b. Dependent Variable: Height of pea plants
c. Control Variable: Plant type (clones), time period, measurement schedule

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Now, let’s write the final answers clearly.

Final Answer:
1)
a. Independent Variable: Type of rose bush
b. Dependent Variable: Number of flowers
c. Control Variable: Greenhouse environment, duration (2 months)

2)
a. Independent Variable: Concentration of salt in water
b. Dependent Variable: Height of sunflower plants
c. Control Variable: Type of plant, time period (2 weeks), watering method

3)
a. Independent Variable: Humidity level (or location/environment)
b. Dependent Variable: Height of redwood trees
c. Control Variable: Tree type (redwood), measurement frequency, duration (12 weeks)

4)
a. Independent Variable: Amount of water given per day
b. Dependent Variable: Height of pea plants
c. Control Variable: Plant type (clones), time period (3 weeks), measurement schedule