science and Technology

Test Your Reaction Time


Do you think you have fast reactions? Have you ever measured your reaction time? There’s an easy way to test reaction times using just a ruler.

Reaction time is the time taken for a person to respond to a stimulus. For example if you touch something very cold, there is a slight delay between you touching it and moving your hand away, because it takes time for the information to travel from your hand, to your brain where it is processed and then a response started. Many sports and activities require fast reactions!

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Reactions are different to reflexes which are involuntary. Reflexes are faster than reactions.

You can test reaction time using just a ruler.

Simple ruler drop reaction time test

What you need

30cm ruler

Pen and Paper


How to test your reaction time

Hold the top of the ruler with your arm stretched out. Your fingers should be on the highest measurement.

Ask a friend to put their thumb and index finger slightly open at the bottom of the ruler, with the ruler between their fingers.

Drop the ruler and record the measurement on the ruler where the other persons fingers are.

Repeat for all participants. Let each person have three attempts and record the average value.

The person with the fastest reaction time is the one who catches the ruler at the lowest measurement, as the sooner the ruler is caught the less time it has had to fall.

Reaction Time Test

How does this work?

Our eyes see that the ruler has been dropped and send a signal to the brain, which sends a signal to the muscles in the arm and hand to tell them to catch the ruler. Our body is very clever and these signals travel very, very quickly.

Information from the eyes is sent to the brain and then to the hand via neurons. The brain processes the information and decides what to do next. The human brain contains around 100 billion neurons!

Your reaction time depends on the time taken for the signals to travel between your eye, brain and hand.

Reaction Time Challenges

Design a table to record the results.

Investigate to discover whether reaction time can be improved with practice. Does muscle memory help speed up your reaction time?

Download the instructions

Reaction Time Test Instructions

More Reaction Time Tests

Repeat the investigation using your non dominant hand, is your reaction time slower?

Design an investigation where you work out the average reaction time for different age groups.

How about tying a piece of string to a toy car, and letting it run down a ramp? You could measure the distance the car travels before you stop it.

Can you think of any more ways to test reaction time? What would you consider a slow reaction time?

Learn more about the brain with our play dough brain model.

If you like this activity you might also like our collection of sporty science experiments for kids.

Quick Summary

Reaction time is the time it takes you to react to a stimulus.

Information is sent around the body via nerve cells called neurones. These form the peripheral nervous system. The central nervous system consists of the brain and spinal cord.

Science Concepts

Reaction timeNervous systemStimuli

Last Updated on August 31, 2022 by Emma VanstoneThe post Test Your Reaction Time appeared first on Science Experiments for Kids.