The Hand Squeeze

A Class Experiment
This activity was adapted from one originally written by Cynthia Lanius, Rice University.

Let's conduct an experiment. We will pass a "hand squeeze" down a line of people and back, and measure the amount of time it takes for the hand squeeze to travel.

Collect the Data:
  1. Appoint a time keeper with a clock or stop watch.
  2. Appoint a recorder to write results in a chart on the board.
  3. Start with two students at the front of the room. Have the two students hold hands. When the timekeeper says "now" the first person should squeeze the hand of the second person who squeezes back when (s)he feels the hand squeeze. The first person will then say “now”. The time keeper will call out the time, and the recorder will write the results on the board.
  4. Now add two more students to the line and repeat the process, passing the hand squeeze down to the end of the line and back. Record that time and repeat the process with two more students.

Continue the experiment, until everyone has joined the line. Have everyone try to pass the squeeze as quickly as they feel it, maintaining the same rate of speed. If someone messes up, it's okay to disregard that time and repeat the experiment.

Number of StudentsTime (seconds)Number of StudentsTime (seconds)
2 18 
4 20 
6 22 
8 24 
10 26 
12 28 
14 30 
16 32 

Graph the Data
  1. Everyone copy the data to the table.
  2. Which is the independent variable (the one we set up in the experiment), and which is the dependent variable (the one we measured)?
  3. Take a piece of quadrille paper and draw two axes. Label the horizontal axis with the independent variable and the vertical axis with the dependent variable.
  4. On each axis, number the squares to fit the data.
  5. Plot each point.
  6. Label the Graph. Use an area of the graph where there are no points. Write an appropriate title.
Analyze the Data:
  1. Should we connect the points? Why or why not?
  2. Are the points scattered all around the plane or do they form a sort of a line?
  3. Draw a best fit line through the points. A best fit line goes as close as possible to all the points.
  4. Find the slope of the line. What does it represent?
  5. Make a prediction: How many seconds would it take to pass the hand squeeze down a line of 100 people and back? How can you use the slope of the line on your graph to determine this?