Scientists Say: Experiment

An experiment is a process used to test an idea about how the world works

If you’ve got a question about how nature works, a scientific experiment can help you find the answer.

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Experiment (noun, “Ex-PAIR-uh-ment)

The word “experiment” might make you think of scientists wearing white coats in a lab. But anyone, anywhere can do an experiment. An experiment is a procedure used to test an idea about the world.

In an experiment, a person manipulates one thing and observes how that may affect another thing. The thing that the person manipulates is the independent variable. The thing that may change in response is the dependent variable.

For example, Science News for Students did an experiment to test the five-second rule. The rule states that food dropped on the floor will collect fewer germs if it’s picked up quickly. To test this rule, you need to compare two things: how long food lays on the floor, and how germy the food gets. In this case, the person doing the experiment manipulates the amount of time the food spends on the floor. How long the food lays on the floor is the independent variable. The dependent variable — the thing that may change in response — is how dirty the food gets.

Measurements of the number of germs on different pieces of food are experimental data. Analyzing data can lead to a conclusion about the idea being tested. In this experiment, the data suggest that time spent on the floor does not affect how many germs get on food. Conclusion: the five-second rule is a myth.

But don’t take our word for it. A crucial part of science is replication. That’s when many scientists do the same experiment to confirm or deny the results. Join the scientific process by doing the five-second rule experiment for yourself. Or try another experiment from our collection.

In a sentence

If you have a question, like which parts of the body are most sensitive to touch, an experiment can help you find out the answer.

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Maria Temming is the assistant editor at Science News for Students. She has bachelor's degrees in physics and English, and a master's in science writing.

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