Variables, Constants, and Control Practice

The independent variable is the variable that you (a)   where as the dependent variable is the variable that you ​ (b)   or​ observe.

• change
• measure
• ignore

• predict

Answer explanation

The independent variable is what you change in an experiment, while the dependent variable is what you measure or observe to see how it responds to changes in the independent variable.

Tags

NGSS.MS-PS3-4

A student rolls toy cars down ramps made of different materials: wood, metal, and cardboard. He measures the time it takes each car to travel one meter. The ramps are the same length and height. What is the dependent variable?

• Ramp material

• Time it takes the car to travel one meter (speed)

• Ramp made of wood (common ramp material)

• Ramp length, ramp height, same toy car, distance measured

Answer explanation

The dependent variable is what is measured in the experiment. Here, it is the time it takes the car to travel one meter, as it depends on the ramp material. The other options are either independent variables or constants.

A student tests how long different brands of batteries make a flashlight stay on. She uses the same flashlight, turns it on at the same time, and records when the light goes out. What is the independent variable?

• Brand of battery

• How long the flashlight stays on (battery life)

• A common brand (like Duracell or Energizer)

• Same flashlight, same bulb, same starting time, same environment

Answer explanation

The independent variable is the 'Brand of battery' because it is the factor being changed to observe its effect on how long the flashlight stays on.

A student wants to find out which brand of paper towel absorbs the most water. She pours the same amount of water onto each paper towel and measures how much is absorbed. What is the dependent variable?

• Brand of paper towel

• Amount of water absorbed

• A well-known or store-brand paper towel

• Amount of water poured, size of paper towel piece, measurement method, room temperature

Answer explanation

The dependent variable is what is measured in an experiment. In this case, it is the 'amount of water absorbed' by each brand of paper towel, as it depends on the type of paper towel used.

Tags

NGSS.MS-LS1-5

The variables in an experiment that stay the same are the:

• IV
• DV
• Constants

Tags

NGSS.MS-PS2-2

A student wants to test how different colors of light affect the growth of bean plants. She places one plant under red light, one under blue light, and one under white light. Each plant gets the same type of soil, the same amount of water, and the same type of pot. What are the constants in this experiment?

• color of lights

• amount of water

• growth of bean plants

• type of pot

• type of soil

Answer explanation

In this experiment, the constants are the amount of water, type of pot, and type of soil, as these factors remain the same for all plants. The color of light is the variable being tested.

Tags

NGSS.MS-LS1-5

A student wants to know if water temperature affects how fast sugar dissolves. She places the same amount of sugar into cups of cold water, room temperature water, and hot water, and times how long it takes to dissolve. What is the control? (what is common and normal)

• Cold Water

• Hot Water

• Room Temperature Water

• Sugar

Answer explanation

The control in this experiment is the variable that remains constant for comparison and is normal. Here, room temperature water serves as the comparison to evaluate how sugar dissolves in cold and hot water because sugar is normally dissolved in room temperature water.

Tags

NGSS.MS-PS3-4

NGSS.MS-PS1-4

The dependent variable in an experiment always goes on the ​ (a)  

• y axis
• x axis

What is the dependent variable?

• Type of fertilizer

• Average plant height

• The effect of fertilizer on plant height

• The effect of plant height on fertilizer

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

On a graph, which axis shows the independent variable?

• x-axis
• y-axis
• neither
• it changes

Tags

NGSS.MS-PS3-1