Science Fair Insider: The Dependent Variable Explained

It’s time for the science fair.

This no-holds-barred grade-school experiment extravaganza is getting more and more complicated as the years go by.

You can’t just build a paper Mache volcano anymore, parents.

These things are way more competitive than that nowadays. In order to construct your child’s experiment, it’s got to have variables.

To use variables appropriately and build a better experiment, you have to understand them. You must utilize them appropriately and realize how they interact with each other within the experiment.

Confused yet?

Never fear.

Read on to discover the power of the dependent variable, and how to use it properly to take your kid’s science fair project from weak to wow in no time flat.

Defining the Dependent Variable in an Experiment

What is a dependent variable?

In order to define it, you first must understand the basics of variables in general.

The variable definition isn’t hard to pin down. It’s basically any factor in an experiment which can be changed in a measurable way. There are three types of variables in any experiment, your kid’s included.

Dependent Variable

Comprehending the dependent variable definition is paramount to a successful experiment.

Guess what? The dependent variable is actually determined by the independent variable.

If it seems kind of like a catch-22 concept, read on.

Basically, the dependent variable is what is being measured or tested in the experiment. Its measurement is the outcome of the test. And by changing the independent variable, you’ll change the outcome for the dependent variable.

For example, say you’ve decided to conduct an experiment on how light affects plant growth. The factor being measured is the growth of the plant. The growth is dependent on the amount of light given, so there’s your dependent variable.

Independent Variable

The independent variable is the one which you manipulate. You measure the effect of this variable on the dependent variable to come up with your conclusions.

Ask yourself which factor you control or change. In your plant experiment, you change the amount of light to measure the effect it has on the plants.

Therefore, the amount of light you give the plant would be your independent variable.

Control Variable

The control variable is any factor that you have to keep constant during your experiment. You don’t want any outside factors influencing your results, so you have to conduct each test in the same manner.

In the plant experiment, the type of plant used would be a control variable.

Importance of the Dependent Variable in a Scientific Experiment

The dependent variable is the entire reason you’re conducting the experiment.

You want to learn more about it, and the effect that different independent variables have on it.

It’s important to choose a dependent variable that’s possible to study in the allotted period of time, and one that will be educational.

It also doesn’t hurt to have a bit of fun.

Choosing a Science Project Based on the Dependent Variable

In choosing a proper science project, make sure you consider the variable you’ll be measuring.

Ask yourself these questions before settling on an experiment:

  • Does this subject hold my child’s interest?
  • Is this subject age-appropriate?
  • Can the dependent variable be measured properly?
  • Can we reasonably conduct the experiment around our day-to-day lives?
  • Is this experiment possible to conduct according to the scientific method required by the school?

You should help your child choose something interesting, but not too complicated. Especially if he or she is closer to primary school than high school.

If you’re stumped about science fair ideas, check out the Science Buddies list of experiment ideas with your child.

You can sort through the list by fields of interest like astronomy, cooking, and environmental science.

Measuring the Dependent Variable in an Experiment

Before you begin any science fair project, think about how you’ll be able to measure the dependent variable. After all, the results must be measurable in order for the experiment to work.

Luckily, there are two ways you can measure results:

  • Qualitative Measurement: A Qualitative measurement is a type of measurement which s recorded using descriptive words. If you are studying the effects of different amounts of light on plants, you can measure the results qualitatively by using language to describe the plants (AKA the dependent variable) descriptively. For example, one exposed to less light could be described as having smaller leaves or a crooked stem.
  • Quantitative Measurement: Quantitative measurement is a type of measurement which can be recorded using numbers. Length, height, age, speed — these are all quantitative measurements. In the plant experiment, the exact height of your plant after being exposed to a certain amount of light would be a quantitative measurement.

Make sure you know which type of measurement is required by your child’s school before deciding on a project. Sometimes, you cannot use both qualitative and quantitative measurements in the same experiment.

Learn About the Dependent Variable to Master Any Experiment

The dependent variable is the diamond in your science fair ring. When you really understand it, you can build a fun and educational experiment experience for you and your child!

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