Independent and Dependent Variables

Independent

vs.

Dependent Variables

​7.N.1.3 - Distinguish between an experiment (which must involve the identification and control of variables) and other forms of scientific investigation and explain that not all scientific knowledge is derived from experimentation. (DoK 2)

The dependent variable, on the other hand, is the variable that is measured or observed in response to changes in the independent variable. It is called the dependent variable because it depends on the independent variable. In the plant growth experiment, the height of the plants would be the dependent variable as it is the variable that we are measuring in response to the different amounts of fertilizer.

Dependent Variable

The independent variable is the variable that is changed or manipulated in an experiment. It is called the independent variable because it does not depend on any other variable in the experiment. For example, if we were conducting an experiment to see if different amounts of fertilizer affect plant growth, the amount of fertilizer we give to each plant would be the independent variable.

Independent Variable

What's the difference?

Multiple Choice

A scientist conducted an investigation to determine the relationship between algae growth and available light at increasing ocean depths. The scientist lowered a light meter into the ocean and recorded the amount of light at different depths. The scientist also collected a water sample at each depth to count the number of algae present. The table below shows the results.

Based on the information in the table, which of the following statements best describes the relationship between light and the density of the algae population?

• As the light level decreases, the density ofthe algae population decreases.

• As the light level decreases, the density of the algae population increases.

• As the density of the algae population increases, it reduces the light level.

• Light level has no effect on the density ofthe algae population.

Multiple Choice

The factor in an experiment that will be changed. 

• dependent variable

• independent variable

• controlled variable

• inferences 

Multiple Choice

Natalie is using a three-dimensional representation to study the parts of the human heart. Isaiah is working in a laboratory to test the hypothesis that plants grow taller in green light than in white light. Which of the following best

compares their activities?

• Natalie is conducting a scientific investigation, and Isaiah is not.

• Natalie is not conducting a scientific investigation, and Isaiah is.

• Natalie is conducting an experiment, and Isaiah is conducting a field study.

• Natalie is investigating a scientific model, and Isaiah is conducting

  an experiment.

Multiple Choice

This part of the experiment serves as a basis of comparison; the one variable being tested has been omitted. (not changed)

• experimental group

• control group

• data

• variables

Multiple Choice

This variable is the actual data collected during the experiment. 

• independent variable

• dependent variable

• control group

• data group

Multiple Choice

Destiny conducted an experiment to test which of four types of batteries lasts longest in a flashlight. She used four identical flashlights and placed a different type of new battery in each flashlight. She turned the flashlights on at the same time, and she recorded the time when each flashlight stopped giving off light. Destiny's data are shown.

What is the independent variable in this experiment?

• the type of battery used

• the type of flashlight used

• the total amount of time each battery lasts

• the starting time when each flashlight is turned on

Multiple Choice

a factor that is not changed in an experiment; all the parts that stay the same to keep the experiment fair and consistent

• variable

• control group

• constant

• evidence

Multiple Choice

Keesha did an experiment to study the rate of photosynthesis in the water plant Elodea. She placed a piece of Elodea in a beaker of water and set the beaker 10 centimeters (cm) from a light source. Keesha counted the bubbles released from the plant every minute for five minutes (min). She repeated the process two more times. First, she moved the light to 20 cm from the beaker, and then she moved the light to 30 cm from the beaker. Keesha’s setup and data are shown below.

What is the outcome variable (dependent variable) in this experiment?

• the number of bubbles produced

• the type of plant placed in the beaker

• the amount of time the bubbles were counted

• the distance of the light source from the plant

Multiple Choice

dependent variable 

• a well tested explanation for a wide variety of observations and experimental results. 

• condition that is controlled so that it does not change during an experiment.

• variable that is observed and changes in response to the variable manipulated by a scientist, variable that is measured.

• is a statement about an observed phenomenon or a unifying conceptproposed explanation or answer to a scientific question.condition that is 

Multiple Choice

Which type of sugar dissolves the fastest?

Which is the independent variable?

• The temperature of the water

• The amount of water

• The type of sugar

• The type of cup you use

Multiple Choice

How much food does a goldfish need to grow?

Which is the dependent variable?

• The type of fish

• How much food you give the fish

• How fast they grow

• The amount of water in the tank

Multiple Choice

A scientist measured the weight of a steel ball on an ocean beach and again on a mountaintop and compared the measurements. The scientist found that the ball weighed slightly more on the beach than on the top of the mountain. Based on this information, which of the following is the most logical hypothesis for the scientist to state?

• As elevation decreases, the force of gravity decreases.

• As elevation increases, the force of gravity decreases.

• Elevation does not affect the force of gravity.

• As elevation increases, weight increases.

Multiple Choice

Keesha did an experiment to study the rate of photosynthesis in the water plant Elodea. She placed a piece of Elodea in a beaker of water and set the beaker 10 centimeters (cm) from a light source. Keesha counted the bubbles released from the plant every minute for five minutes (min). She repeated the process two more times. First, she moved the light to 20 cm from the beaker, and then she moved the light to 30 cm from the beaker. Keesha’s setup and data are shown below.

What is the outcome variable (dependent variable) in this experiment?

• the number of bubbles produced

• the type of plant placed in the beaker

• the amount of time the bubbles were counted

• the distance of the light source from the plant

Multiple Choice

Christopher states the hypothesis that a mouse's body temperature decreases as the air temperature around the mouse decreases. He wants to design an experiment to test his hypothesis. What should the dependent variable be in

this experiment?

• the air temperature

• the mass of the mouse

• the mouse's body temperature

• the amount of time for the experiment