Independent and Dependent Variables

In a controlled experiment, how many independent variables can be tested at a time?

• one

• none

• two or more

• how ever many makes sense.

The variable that is measured.

• Controlled Variable

• Dependent Variable

• Independent Variable

Changes in the _________ variable causes changes in the _________ variable.

• independent; dependent
• dependent; independent

The height of a bean plant depends on the amount of water it receives.

What is the independent variable? (the factor that is changed)

• The height

• The amount of water

• The bean plant

Why is it important to have only one independent variable and to control the other variables when performing science experiments?

• So you can tell which factor is causing the change in the experiment.

• It does not matter, you can have as many independent variables as you want.

The factors that stay the same or are constant throughout the experiment.

• Controlled Variable

• Dependent Variable

• Independent Variable

Cindy wanted to find out how the amount of sunlight affects the growth of plants. She placed two tomato plants in 10 inch pots with potting soil and watered them ¼ cup each day. One plant was placed under a cardboard box and one was placed in the sunlight. She measured the growth of the plant each week for three weeks.

What is the independent variable?

• Using the same type of plant

• Each plant was placed in a 10 inch pot

• The growth of the plant

• One plant is in the sunlight and the other is under a box

Cindy wanted to find out how the amount of sunlight affects the growth of plants. She placed two tomato plants in 10 inch pots with potting soil and watered them ¼ cup each day. One plant was placed under a cardboard box and one was placed in the sunlight. She measured the growth of the plant each week for three weeks.

What is the dependent variable?

• Using the same type of plant

• Each plant was placed in a 10 inch pot

• The growth of the plant

• One plant is in the sunlight and the other is under a box

A study was done to find if different tire treads affect the braking distance of a car.

What is the dependent variable? (the factor being measured)

• Tire treads

• The car

• The braking distance

The one factor that a scientist changes during an experiment.

• Controlled Variable

• Dependent Variable

• Independent Variable