Test Your Reaction Time

Do you think you have fast reactions? Have you ever measured your reaction time?

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.

You can test reaction time using just a ruler.

What you need:

30cm ruler

Pen and Paper



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 fingers are.

Repeat for all participants. You could 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.

Test Reaction Time

What happens?

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.

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

Can you improve your reaction time with practice?

Can you design a table to record your results?

Test reaction time

Can you think of any other ways to test reaction time? 

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 anything else?

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