Reaction Time


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Experiment Category: 


Participants will explore reaction time and challenge themselves to improve their time.

What You Need: 

  • Yardstick or long ruler
  • Partner to work with
  • Paper
  • Pencil

To Do and Observe: 

1. Hold the ruler at the top so that you are pinching the highest number and the lower numbers hang down. 

2. Have your partner place her thumb and index finger about an inch apart on either side of the bottom of the ruler without touching it. 

3. Have her practice pinching the ruler using her fingers; this is how she will catch the ruler to measure her reaction time. 

4. Tell your partner that you will drop the ruler and she should catch it fast as she can, using her thumb and index finger. 

5. Drop the ruler. 

6. Record the distance that your partner caught the ruler. 

7. Use the table below to convert distance to reaction time and record that time. 

8. Do this 10 times, recoding your results, and then switch roles.

What's Going On: 

Reaction time, or response time, is the time between any kind of event and the response it elicits in a system. Superstar athletes are not born knowing how to hit a fastball or dive to dig a volleyball. Sports are made up of skills that athletes practice over and over in order to improve. Reaction time improves with practice, and practice can mean the difference between getting the fast start you need to win a race, or intercept a football pass, and just missing by a fraction of a second. 

The brain is an essential part of developing a quick reaction time. Normally we make an observation using our senses, like touching a cold ice cube, hearing a train, smelling a fire, etc. In this activity our observation was seeing the ruler fall. This information travels along our nerves to our brain as electrical signals. The brain processes this information, then sends a signal back through our nerves to our hands, telling us to close our fingers to catch the ruler. The amount of time this all takes is what makes up our reaction time. 

A quick reaction time can also help you avoid danger. For example, if you’re crossing the street and you hear a car horn, you want to get out of the way fast! It’s not only people that depend on reaction time; lots of animals depend on a fast reaction time to keep them from being eaten or finding food for themselves.

Parent/Teacher Tips: 

For Younger Participants
Before doing the activity above, you can play a quick game of catch to show participants how they react to certain situations. You have them catch and throw the ball to one another and talk about how quickly they can do this. You can also talk about the five senses and talk about how they help us to make observation (find out about the world around us). 

For Older Participants
Have the participants hold a stopwatch in their other hand. As soon as they drop the ruler, they start the clock and when their partner catches the time stops. Compare the time on the stopwatch to the chart above. Were they the same or different? How can the difference be explained?