# Identifying Variables

When you are evaluating a research summary you should take special care to identify the variables in the experiment.

The variables in the basic experiment can be either independent or dependent.

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Question 1 of 2

A tall man feeds his cows different amounts of food each day. He notices that the cows are happier on days when they receive the most food. In this situation, what is the independent variable?

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B.
C.
D.

Question 1 of 2

Question 2 of 2

A control variable

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B.
C.
D.

Question 2 of 2

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The transcript is for your convenience.
We’ll start with independent variables. The independent variable in an experiment is the aspect of the experiment that is changed by the scientist on purpose.

Then you have the dependent variables. A dependent variable in an experiment is the aspect that responds to changes that are made in the independent variable. We have cause and effect here.

Independent causes the dependent variable to change and so the independent variable is manipulated by scientists on purpose so that we can see the effect of it on the dependent variable. While the independent variable is manipulated, the dependent variable is just observed to see the changes that take place in it.

Now, it’s important to be able to identify the independent and dependent variables in an experiment. Let’s take a look at this example. An experiment exploring how plastic reacts to different amounts of heat, so here we’re taking a look at plastic and its response to heat.

The independent variable here is going to be temperature because we’re looking at cause and effect here and we’re looking at how plastic responds to heat. The temperature here must be the independent variable because that’s what we’re trying to changing around to see how plastic responds.

That leads us to the dependent variable, which is going to be the plastic because we’re seeing or observing how the plastic reacts to the different amounts of heat.

Again the independent variable is the aspect of the experiment that is changed and the dependent variable is the aspect that responds to changes made in the independent variable.