Scientific method variables (worksheet) | PDF - Free Printable

Based on the image provided, here is the solution and explanation:

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1. What is the student's change variable?

✔ Correct Answer: c. the brightness of the light the plant is growing on

Explanation:
In a scientific experiment using the scientific method, the change variable (also called the independent variable) is the one thing the experimenter deliberately changes to observe its effect.

Looking at the two setups in the image:
- The plant on the left is under a brighter, more intense light.
- The plant on the right is under a dimmer light.
- All other aspects (type of plant, pot, soil, position, angle of lamp) appear identical.

The only intentional difference between the two setups is the brightness/intensity of the light shining on the plant. Therefore, this is the independent (change) variable.

Let’s eliminate the others:
- a. *angle of the light* — appears identical in both images.
- b. *type of soil* — not shown to be different; assumed same.
- d. *temperature of the air* — not indicated as being changed or measured differently.

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2. List all the control variables that you can see that the student is keeping constant (the same)

Here are the variables the student is likely keeping constant (control variables):

✔ Control Variables (Constants):

- Type of plant – Same species and size of plant used in both setups.
- Pot type and size – Identical pots are used for both plants.
- Soil type and amount – Assumed to be the same (same container, same appearance).
- Position of the lamp relative to the plant – The lamp is placed at the same height and distance from each plant.
- Angle of the light source – The lamps are positioned identically above each plant.
- Duration of light exposure – Although not explicitly shown, it’s implied the plants are exposed to light for the same amount of time (otherwise, it wouldn’t be a fair test).
- Watering schedule – Not shown, but assumed to be the same for both plants to avoid confounding results.
- Room/environmental conditions – Temperature, humidity, and air circulation are assumed to be the same unless otherwise stated.

> 💡 *Note: Control variables are factors kept constant so that any observed effect can be confidently attributed to the change variable (light brightness).*

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Summary:

- Change Variable (Independent Variable): Brightness of light
- Control Variables: Type of plant, pot, soil, lamp position/angle, duration of light, watering, environment (temperature, humidity), etc.

This setup allows the student to fairly test how light brightness affects plant growth (e.g., height, leaf size, health), which would be the dependent variable (not asked here, but implied).

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✔ Final Answers:

1. c. the brightness of the light the plant is growing on

2.
- Type of plant
- Pot used
- Soil type and amount
- Position and angle of the lamp
- Duration of light exposure
- Watering schedule
- Environmental conditions (temperature, humidity)

*(You can list any 4–6 of these — they’re all valid control variables based on the image.)*