Tuesday, June 28, 2011

On thermometers

I got sidetracked from science for a bit. Governor Christie came to our school back in March for a private meeting; our Ed Commissioner Chris Cerf tagged along, and took exception to my opinion of his past work. We met again, and then again, though I'm still not clear why.

At any rate, my foray into politics has apparently ended--Trenton is silent, my orneriness again overwhelming what talents I may have. At least I got to spend an hour in the commissioner's glass office, overlooking the Delaware River. I like the Delaware more than I like offices, so next time I'll stay outside.

Back to science. If I should stumble onto anything that might help kids, Mr. Cerf, feel free to use it.

We teach a lot of pseudoscience. We praise Aspergerish behaviors in science class. We rewards those children who can mimic our stories, but not those who create new ones.

What does a child know measuring temperature? What do any of us know? A classroom thermometer is a disarmingly simple gadget--a glass tube with some dyed alcohol in it. The way we use them, though, they may as well be cast from the Temple of Delphi.

Alcohol, like most stuff, expands when heated. We tell kids that, and they write it down, spit it back, and wham, we just bypassed one of the most basic and interesting facets of physical science a child will ever get a chance to know.

Let's explore it a bit further....

If we shove some alcohol in a tube, leave some space, then seal off the top, we have a thermometer. Gas is far more compressible than liquid, so as the alcohol warms up, it rises up the column. At some point we need to calibrate it, but let's leave it blank for now and give it to a 7 year old.

What can she do with it?

She can watch what it does. Warm things (whatever warm means, and for mammals it's truly relative) it rises, for cool things, it shrinks.

Can a 7 year old grasp that if the liquid rises to the same point that an object has the same temperature? This is a far more difficult concept that it appears. Most adults wouldn't get it. We all talk about temperature, but few of us know what we're talking about.

But let's get back to the thermometer....

If the alcohol expands, and we did not add anything to the tube, and we accept the idea that atoms exist, then only a few things could have happened. Either the atoms got bigger themselves, the space between the atoms got bigger, or both.

We're not talking about trivial volumes. You neglect this, and bridges fall down. Our whole story about physical science depends on our concept of atoms. Few of us grasp the model, and even fewer grasp that it's just a model.  We kill science long before a child has a chance to shave unwanted hairs.

We place far more emphasis on the ability to read the thermometer than on the story behind why alcohol expands when heated. The story is not hard to grasp. The particles of alcohol vibrate more as they "warm up"--Michael Jackson needed more space dancing than, say, sleeping.

Temperature is defined as the average kinetic energy of particles in a given lump of stuff--kinetic energy is all about motion. The more actively you dance, the more kinetic energy you have. (To be fair, a physicist would argue I put the cart before the horse--the dancing reflects the kinetic energy.)

So tell the 2nd grader the story--the more active the particles are, the warmer they feel. The more the alcohol particles dance, the more space they need. Why? Because....

The "because" dictates the story--we forget this, but children do not. Everything is "because" when you're young. The stories help us sort out the "becauses"--and ultimately, much of this is unknowable.

If I were king of the world, thermometers in early elementary school would not be calibrated. They would not even have lines. They'd just be sticks of colored alcohol, lying about in class. The less said, the better....

For a high school student, this is not a trivial matter. We tell them that the molecules are vibrating more, but what does this mean?

We feel "heat"--or rather, our brain processes afferent signals, and determines that skin molecules are vibrating a bit faster than they were a moment ago. Our brains do not love our models--if they did, science would be intuitive. There's a reason, a good one, that sophomores are more interested in sex than science.

It you put one hand in cold water, and the other in hot, then put both in tepid water, the former will feel warm, the latter cold. It's an easy demo for class, and one worth doing. For survival, knowing whether something is warmer or cooler is enough. The thermometer belies our bias.

So we create our stories. If we're going to teach science, we're going to have to stumble along with our stories. There's no other way.

(Yes, I know our stories are bound by what we observe, and are often more easily represented by mathematical models--but we are talking of children, most who will fail in Arne's dream of creating a generation of technophiliacs.)

It gets down to matter, and energy, and we do a lousy job explaining either to our little ones, partly because they're hard to grasp, but more so because we fear admitting what we don't know.

If our goal is more engineers, then maybe pushing the stories as reality, concrete as the brains running ed reform, makes sense.

Science, alas, is grounded in the universe, which is to say, it's not grounded at all--the pieces are flying all over the place, each fragment related to every other, but flying all over nonetheless. It's messy, but despite the mess, possibly (possibly) reducible to a few general principles.

I could spend a month playing with thermometers and heat in class, but I do not have that kind of time. I'm supposed to teach biology.

Our high school has several patches of "dog vomit" slime mold bubbling about the school grounds, one patch oozing a bloody red liquid. I just found it today.

This is great stuff! Utterly incomprehensible oozing life forms just a few feet from our school's doors. I will fence it off tomorrow, and ask the custodians to leave it be.

Here's the catch--while we pretend that the icky stuff is what we need to capture our kids' interest, the science behind our lowly cheap thermometers would be more than enough to hold the interest of our students if we were more interested in sharing our ignorance of this universe thing than if we were trying to raise engineers.

I've got nothing against engineers--some of my best friends....you get the idea.

We got colleges for engineers. I just want to teach science, the kind based on observations of a universe we cannot possibly hope to grasp perfectly, but one that we can hope to grasp enough to know it more than most of us do.

Enough to know the meaning of finite, the meaning of enough, the meaning of *blush* love.

What do any of us truly know?
Slime photo by Ivo Antuske, who released it to the PD'
The Gov's photo from our school's website.

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