I talk a lot of science on this here blog. It’s kind of my thing. It’s right there in the name, for Pete’s sake. And I have offered hundreds, nay thousands, of the best, most interesting, most important, highest quality, easy scientific experiments you can perform with your students to hopefully shut them up for a little while. Basically, I want you to like science as much as I do, so you can (hopefully) pass on that enthusiasm to the smelly little goobers who fill up your classroom every weekday.
All that said, this week’s Demo Science science demo is do something we’ve never done before: question the science of our science. In scientific research, objectivity should always be the rule. This experiment will illustrate that subjective measurement is unreliable, almost uniformly incorrect, and thoroughly unfit for scientific study.
Frightfully Inefficient Hand Washing
For this lil’ ol’ experiment, you’ll need three identical drinking glasses (and by gods I mean absolutely identical—this demonstration will not work and someone will likely be severely injured if those glasses are 100% the same in every conceivable way*), a portion of lukewarm water, an equal portion of hot (not boiling) water, and an equal portion of ice water.
You’ll likely want to replicate this with a few different sets of glasses and waters, so your students can play along perform this very serious science experiment on their own as you lead.
Fill each of your three glasses with one of your assorted waters. Label them or arrange them in such a way that you’ll remember which is which. I recommend hot on the left, cold on the right, and room temp in the middle, but that’s just me. Do your thang.
Next, simultaneously place the finger of your choice from one hand in the hot water and the corresponding finger from the other hand in the cold water. Keep them there for at least a full minute.
Not that your fingers are, respectively, quite cool and quite warm, dunk them, one at a time, in the room temperature water. Have your students take note of the (seeming) temperature differences their stinky little fingers relay to their tiny little brains.
Unless you’ve some sort of weird, bizarro fingers, you noticed that when your hot water finger was in the lukewarm glass, the water felt cold, and, conversely, that your cold water finger told you the room temp water was hot. These are an example of the above-mentioned subjective measurement. The “cold” and “hot” you felt are only relative to your individual fingers and are a result of their previous environment.
From this, students can glean that subjective measurements are “personal” measurements—incorrect and unreliable because they are relative to something else and will differ from person to person. The only truly scientific way to measure the water’s temperature—the objective way—is with a thermometer. Thusly, one will find the actual, quantified temperature, an unquestionable result that can be recorded and referenced with certainty.
HAPPY NEW YEAR FROM DEMO SCIENCE. WE HOPE YOUR 2016 IS JUST SWELL!
* Not really. Just use whatever. It doesn’t matter.**
** Or does it?!***
*** It doesn’t.