Thursday, June 30, 2011

Thermometers, again

Thermometers work by magic, or may as well, given the  way we use them in class.

Lorin King, released under CC 3.0

We focus on how to read them, then how to convert one reading to the other. If a child barely has a grasp on Fahrenheit, it's really too much to ask her to convert to Celsius, not matter how much more sense it might make. Kelvin is just Celsius with a degree in pedantics.

A child can observe the triple point of water, at least two parts of it. (Water vapor is invisible--the fog you see is condensed water--droplets of liquid.) A child can tell when water is boiling.

Give a child a thermometer without numbers, without lines. Let her figure out why calibration matters. Otherwise a thermometer is just another talisman in a republic that cannot survive magical thinking.

The worksheet made by Lorin King, released under CC 3.0


Jenny said...

This is not related to your main point, but I have to ask. What is wrong with us that we use the most complicated, ridiculous systems of measurement? Once you mentioned that Celsius makes more sense than Farenheit I realized that we are incapable of choosing a reasonable measurement system.

doyle said...

Dear Jenny,

We use it, because we always have, and change is difficult once you "feel" Fahrenheit.

The story of how Fahrenheit came to be is fascinating. In order to create a scale, you need references, no easy task if you don't have a reliable thermometer to work with.

Fahrenheit made thermometers that gave the same temperature reading in the same conditions, a huge deal. We forget this, and because we forget this, we teach magic instead of science.

Leslie said...

Seriously off-topic, Michael, but your mention of Kelvin made me think of that movie we saw, what, 30 years ago? so I googled "sitting around the Kelvins" to figure out it was "Battle Beyond the Stars."

Back to science now.....