Experiment facts for kids

An experiment is a special kind of test. Scientists and engineers use experiments to check their ideas. They want to see if their ideas match how the real world works. Experiments have helped people learn about the world for a very long time. They are a key part of the scientific method. Many experiments are called controlled experiments. Some are even blind experiments. Often, experiments happen in a laboratory.

Experiments can show us if an idea is wrong. They cannot prove an idea is always true. For example, Albert Einstein had an idea about gravity. He thought gravity could bend light. It took years for astronomers to test this. His idea, called General relativity, said light would bend near a huge object. This effect has been seen when light from distant stars passes the Sun.

Now, many years after Einstein shared his ideas, many tests have been done. All of them have agreed with Einstein's predictions. But, one day, we might find a limit to his theory. What we test are the effects of the theory. The theory itself is too big to test all at once.

"The universe does not tell us when we are right, only when we are wrong." – Karl Popper

What Are Controlled Experiments?

A controlled experiment is a type of comparison. It often compares results from test samples with control samples. Control samples are almost the same as the test samples. The only difference is one specific thing. This one thing is what you are testing (the independent variable).

A good example is testing a new medicine. The group getting the new medicine is the experimental group. The group getting a placebo (a fake medicine) or an older treatment is the control group. This helps scientists see if the new medicine really works.

Experiments vs. Observational Studies

An observational study is used when an experiment is hard to do. It might be too difficult, not ethical, or too expensive. Observational studies are not the same as experiments.

Experiments let researchers control other factors. They can also change one specific thing to see what happens. Observational studies often do not use random samples. They also often have many different things happening at once. This makes it harder to find clear causes and effects.

Famous Experiments in History

Many important discoveries came from famous experiments:

• Galileo Galilei did experiments about how things fall (called free fall) in 1623.
• Benjamin Franklin showed that lightning is a form of electricity in 1752.
• The Michelson–Morley experiment in 1887 found a problem in old physics ideas. This led to Albert Einstein's work.
• Ivan Pavlov did experiments in 1927 about how dogs learn through classical conditioning.
• The Avery–MacLeod–McCarty experiment in 1944 proved that DNA is the molecule that carries heredity (how traits are passed down).
• Stanley Milgram showed that people often follow orders. This became known as the Milgram experiment in 1961.

Images for kids

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  The black box model for observation (input and output are observables). When there is a feedback with some observer's control, as illustrated, the observation is also an experiment.

See also

In Spanish: Experimento para niños