Reaction Time

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Author: Nancy Rogers Bosse

Grade Level: 3rd - 5th; Type: Physical Science


To investigate the difference in reaction times between boys and girls.

Research Questions

  • Is the reaction time between boys and girls different?
  • Can you improve your reaction time?
  • Can all reaction times be improved?

Reaction time is the length of time it takes to respond to a stimulus. Reaction time is important when driving, when playing sports, in emergency situations, and in many day-to-day activities. Reaction time depends on nerve connections and signal pathways. Reaction time is the measurement of how long it takes for brain and nerves to react to a stimulus.


  • 10 boys and 10 girls between the ages of 10 and 12
  • ruler
  • stopwatch
  • paper
  • pencil

Experimental Procedure:

  1. Gather the necessary materials.
  2. Gather 10 boys and 10 girls who are similar in age to participate in your experiment.
  3. One at a time, test each volunteer’s reaction time by having the volunteer sit beside a table with his or her arm on the table and his or her hand extending off the edge of the table. Hold the ruler so that its bottom end is just between the volunteer’s thumb and index finger. Without warning, release the ruler while the volunteer closes his or her fingers as quickly as possible on the ruler. Note how many inches the ruler fell by looking where the volunteer grasped the ruler. Use the chart below to determine the volunteer’s reaction time. Repeat the procedure 4 times, recording each reaction time.
  4. After testing the reaction time of the volunteer, determine the average reaction time by adding the reaction times together and dividing by five (the number of tests). Record the results.
  5. Repeat steps 3 and 4 for each volunteer.
  6. After completing the reaction time test with each of your volunteers, analyze the data and draw a conclusion.

Terms/Concepts: reaction time: the time between a stimulus and a response stimulus: something that causes an action or response response: a reaction to a stimuli sensory receptors: parts of your body that respond to stimuli; Reaction time is the length of time it takes to respond to a stimulus. Reaction time depends on nerve connections and signal pathways from the skin (touch), eyes (sight), ears (sound), tongue (taste), and nose (smell) to the brain. Some reaction times occur naturally such as blinking to cleanse the eyes. Other reaction times are the result of a choice and can be improved with practice such as learning to swing a baseball bat. Athletes work hard to improve their reaction times.


“Reaction Time” at “Reaction Time” at “Stimulus – Response: Reaction Time” at

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