In experiments, scientists use careful methods to ensure their results are accurate. In an experiment, variables are the things in experiments that can exist in differing amounts or types. Variables can be either independent or dependent and both are necessary for a true experiment. Think about the variables in the following experiment:

Jane conducted a simple experiment to see which soil would make her tomato plants grow the tallest. She planted two groups of tomato plants in her back yard, ensuring they all got the same amount of sunlight and water. She planted the two groups in different types of soil and recorded the results.

Select all true statements about Jane's experiment and scientific variables.

In Jane's experiment, the type of soil she used was the independent variable.

Dependent variables are the things measured and observed in an experiment.

Dependent variables are what is tested in an experiment.

Jane could also measure leaf width as an independent variable.

Independent variables are changed by the scientists in an experiment.

In Jane's experiment, plant growth was the dependent variable.

Independent variables remain the same for all experiments.

Jane could try this experiment again, using fertilizer instead of soil as a dependent variable.