Stinky Science

Problem: Who has the fastest and slowest reaction times in this science classroom?

Research:  What is reaction time?




            Paper Clip

Piece of Lined Composition Paper



Procedure A:

  1. Take one of the pieces of composition paper, while holding it with the margin at the bottom; fold it in half lengthwise so it is 11 inches long and 4.25 inches wide.

  2. Keep the margin at the bottom of the paper and begin numbering on the bottom line with the number “0” until you have placed a number on each line.

  3. Staple the two sides together.

  4. Place a paper clip at the bottom of the paper (or tape a penny to it)).  You have made your reaction time tester.

  5. Get a partner, one of you will drop the other will be tested for your reaction time.

  6. The person being tested will have their thumb and forefinger 1 inch apart.

  7. The dropper will ask the tester, “Are you ready?”

  8. The tester will respond by saying, “OK.”

  9. The dropper will then drop the paper straight down.

  10.    The tester will close their fingers as quickly as possible and hold the paper.

  11.   The dropper will record the number of the line that the testers fingers are on.

  12.   Repeat this until 10 trials have been recorded for each person.

  13.    Find the mean (average) reaction time for each person.  (If you do not remember how to figure out the average, ask another group.)

  14. To figure your reaction time in seconds use the following formula:
             Seconds = sqrt (avg. lines / 980). 
    In words this would be "your reaction time in seconds = the square root of your average number of lines divided by 980.  Click here if you want to know the rationale for the formula and learn about velocity and and acceleration of gravity. 

Data Table:

Trial Data Set A
Your Reaction Time (in lines)
Data Set B
Your Reaction Time (in lines)
Average Reaction Time (in lines)    
Average Reaction Time (in sec.)    

Questions to ponder:

  1. Who were the fastest and slowest individuals in the class?

  2. Do you think the lineup of students from fastest to slowest achieved scientific truth?  Why or Why not?

  3. What were the extraneous variables in data set A?

  4. How would you control for each extraneous variable if we were to do this again?

Data Set B:  

  1. Implement all the controls for extraneous variables and do the experiment again.

  2. How did the first data set compare with the second data set for you personally? Explain!

  3. Did the line up of students from fastest to slowest change significantly?  Explain.

  4. What did you learn from this exercise about science?