When I was at the Exploratorium in San Francisco, I learned a technique for grouping students for activities in a class by shaking hands and feeling the temperatures. The temperature of human hands varies from individual to individual. Human hands can easily sense the temperatures of other hands.
To investigate we can ask our students to shake hands with other students in the class and notice the temperature of the other hands. Most likely, the students will have hotter or colder than their own hands.
After shaking hands with many people, arrange them in a line from hottest hands at one end to coldest hands at the other. Then have the hottest handed person and the coldest handed person divide the line into two equal groups- Hot handed group and cold handed group. We can also extend this activity by making the hot handed person and the cold handed person go down the line shaking hands with everyone else to find out the differences.
What’s going on?
Human hands have different temperatures. The temperature depends on the metabolic rate and circulatory system of each individual. If a person’s vascular system is dilated (which is what we call vasodilatation), their hands tend to be hotter, if it is constricted (vasoconstriction), their hands tend to be colder.
We can also try this activity with an adult who smokes and drinks alcohol. First do the above activity then allow the smoker to take a break to smoke . When they return have them shake hand and experience the difference. Nicotine in cigarette smoke is a vasoconstrictor and will cause their hands to become cooler. On the other hand alcohol is a vasodilator and will cause their hand to become warmer.
In addition to using this information for grouping a class, it can be the entry point to a number of lessons, from anatomy to physics even hygiene. Be sure to wash your hands after touching so many people, hands are the number one way to spread germs.