Science: Variables in Experiments Worksheet

Question 1

A student tests how the amount of sunlight affects the height of bean plants. She places one plant in full sunlight, one in partial sunlight, and one in darkness. She waters each plant with the same amount of water each day. What is the independent variable?

Accepted Answer

The independent variable is the amount of sunlight each bean plant receives, because that is what the student changes on purpose.

Question 2

In the bean plant experiment, what is the dependent variable?

Accepted Answer

The dependent variable is the height of the bean plants, because that is what the student measures to see the effect of sunlight.

Question 3

In the bean plant experiment, name two controlled variables.

Accepted Answer

Two controlled variables are the amount of water and the type of plant. These are kept the same so the test is fair.

Question 4

A class investigates whether water temperature affects how fast sugar dissolves. They use cold water, room temperature water, and hot water. They put 5 grams of sugar in each cup and stir each cup 10 times. Identify the independent variable, dependent variable, and one controlled variable.

Accepted Answer

The independent variable is the water temperature. The dependent variable is how fast the sugar dissolves. One controlled variable is the amount of sugar, the number of stirs, or the amount of water in each cup.

Question 5

A student wants to know if different brands of paper towels absorb different amounts of water. What should the student measure as the dependent variable?

Accepted Answer

The student should measure the amount of water absorbed by each paper towel, because that is the result being tested.

Question 6

A student tests which type of fertilizer helps grass grow tallest. He uses the same kind of grass seed, the same soil, the same amount of water, and the same amount of light for all trays. What is the independent variable?

Accepted Answer

The independent variable is the type of fertilizer, because that is the factor the student changes between the trays.

Question 7

For the fertilizer and grass experiment, explain why the same soil, water, and light should be used for all trays.

Accepted Answer

The same soil, water, and light should be used so those factors do not affect the results. Keeping them controlled makes it more likely that any difference in grass height is caused by the fertilizer.

Question 8

A science group records the following results for a ramp experiment: a toy car travels 40 cm from a low ramp, 70 cm from a medium ramp, and 110 cm from a high ramp. What is the dependent variable?

Accepted Answer

The dependent variable is the distance the toy car travels, because that is what the group measures after changing the ramp height.

Question 9

In the ramp experiment, name two variables that should be controlled.

Accepted Answer

Two variables that should be controlled are the same toy car and the same starting position on the ramp. These should stay the same so only the ramp height changes.

Question 10

A student asks, 'Does the color of light affect the number of bubbles produced by an aquatic plant?' The student shines red, blue, and green light on the plant and counts bubbles for 5 minutes each time. Identify the independent and dependent variables.

Accepted Answer

The independent variable is the color of light. The dependent variable is the number of bubbles produced by the aquatic plant in 5 minutes.

Question 11

A student wants to test whether music volume affects how well people remember a list of words. Write one controlled variable that should be kept the same for all participants.

Accepted Answer

One controlled variable is the word list, because all participants should try to remember the same words. Another possible controlled variable is the amount of time given to study the list.

Question 12

A group compares how quickly ice melts on different surfaces: metal, plastic, and wood. They use ice cubes of the same size and keep the room temperature the same. What is the independent variable?

Accepted Answer

The independent variable is the type of surface, because the group changes the surface to see how it affects melting time.

Question 13

For the ice melting experiment, what is the dependent variable and why?

Accepted Answer

The dependent variable is the time it takes for the ice to melt, because it is the measured result that may change depending on the surface.

Question 14

A graph shows plant growth after different amounts of fertilizer are added. The x-axis is labeled amount of fertilizer in grams, and the y-axis is labeled plant height in centimeters. Which axis shows the independent variable, and which axis shows the dependent variable?

Accepted Answer

The x-axis shows the independent variable, which is the amount of fertilizer in grams. The y-axis shows the dependent variable, which is the plant height in centimeters.

Question 15

A student says, 'My experiment has two independent variables: amount of water and amount of sunlight.' Explain why this could make the experiment hard to interpret.

Accepted Answer

Changing both the amount of water and the amount of sunlight could make the experiment hard to interpret because the student would not know which variable caused the result. A fair test usually changes one independent variable at a time while controlling the others.

Science: Variables in Experiments

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