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Reaction Time

Reaction Time: Students time how long it takes to catch a dropped ruler


Ruler (older kids) or yardstick (younger kids)


  • Hold the ruler near the end and let it hang down
  • Have another person put his or her hand at the bottom of the ruler and have them ready to grab the ruler (however, they should not be touching the ruler)
  • Tell the other person that you will drop the ruler sometime within the next 5 seconds and that they are supposed to catch the ruler as fast as they can after it is dropped
  • Record the level (inches or centimeters) at which they catch the ruler
  • Test the same person 3 times (vary the time of dropping the ruler within the 5 second "drop-zone" so the other person cannot guess when you will drop the ruler)

    Alternative Experiments

    • Have the person catching close their eyes
      • Say "drop" when dropping the ruler
      • Or tap their foot when dropping the ruler
        How does reaction time change from having eyes open? Which method is faster/slower?
    • Try the experiment in dim light. Does reaction time increase, decrease, or stay the same? Can you explain your results?
    • Compare boys vs. girls. On average, are the boys or girls faster?
    • Compare different ages. Who is faster - the older students or younger students?
    • Compare the scores after practice. Does reaction time improve with practice?
    • Compare kids' scores vs. parents' scores. Who is faster?

    Discussion Points

    • In the first experiment, the signal needs to pass from the eyes, to the brain, to the spinal cord and then out to the muscles
    • In the alternative experiments, the signal either travels from the ear (saying drop) or from the foot (tapping the foot) before heading to the brain. 
    • There are times when reaction time isimportant, such as pain reflexes, like when you step on something sharp or touch something hot

    Faculty Coordinators
    Valerie Hedges, PhD
    Casey Henley, PhD
    Jenny Taylor, PhD


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