Friday, January 7, 2011

Faith and fear

For I took an Earthen vessel, in which I put 200 pounds of Earth that had been dried in a Furnace, which I moystened with Rainwater, and I implanted therein the Trunk or Stem of a Willow Tree, weighing five pounds; and at length, five years being finished, the Tree sprung from thence, did weigh 169 pounds, and about three ounces... I again dried the Earth of the Vessell, and there were found the same two hundred pounds, wanting about two ounces. Therefore 164 pounds of Wood, Barks, and Roots, arose out of water onely.

Jean Baptista van Helmont
Early 17th century experiment

That's how it works. You observe the natural world, take a stab at explaining it, and get it wrong. Van Helmont could have stayed on sure footing--the "stuff" of the tree did not come from the earth he used.

This week I am asking my lambs to memorize the photosynthesis equation. I have them breathe on their hands to remind them what "stuff" plants need for this (carbon dioxide and water), and the warmth of the breath reminds them that the plant needs energy to put the stuff together.

The warmth is sunlight transformed--to chemical bonds in plants, now to body heat.

The words "carbon dioxide" mean little to most, and many keep calling it "carbon"--I've broken a lot of pencils to show them what carbon looks like.

And yet I insist on teaching them that plants take it in on little more evidence than faith in me or in their fear of failing. Faith and fear may work for that old tyme religion, but it should have little place in a science class.

Which makes me a hypocrite--from the Greek hypokrites or "pretender" [Online Etymology Dictionary].

Van Helmont's experiment is wondrously flawed--he wanted to show that water feeds plants, but shoved 200 pounds of dirt between his willow and the water. He should have just planted the willow in plain water. (I learned this from David R. Hershey, who talks about this in a fun article "Digging Deeper into Helmont's Famous Willow Tree Experiment, " The American Biology Teacher, 1991.)

My students fear failure in class, and not irrationally. Failure kills students in public education.

We grow all kinds of things in class. Just this week, a child took home a fully formed carrot that grew in peat moss, fed by our breath and the water she gave it.

If I asked a very smart kindergartener how a plant grows seemingly from nothing, she might raise an eyebrow with an incredulous look--"It ate the water!"--how can a grown-up be so dense.

If I ask a sophomore, many will stumble, trying to give me sciency jargon. At least the kindergartner got it half right.

Unlearning is hard. My students have been blowing on their hands for 4 months now, since the first week, when we discussed why a candle (or anything else in the classroom) burns.

Over and over and over again I break things down into two categories--"stuff" or energy.

When you burn something, you end up with exactly the same amount of stuff you started with. Exactly, down to the atom. For all the light and heat and sound that erupt in from my lit propane torch, none of that energy cost an atom.

I sweep the propane torch on a large flask, fogging the glass with water, water that did not exist until that moment. I can talk of electrons and oxygen and energy states, but that's a lot of theory to toss out based on a little bit of fog from flame.

Faith, boys and girls, faith. And there's a test in two days. Fear, girls and boys, fear.

And why do I comply. Fear and selfishness. I love teaching, and pretend that I can slip some science in now and again. Right now the tests are winning.


Part of me believes that if I can get my students thinking, really thinking, they will do fine on the state exam. I'm not convinced. So long as the exam asks students to discuss invisible gases, I've got to push faith in the classroom. Ironically, van Helmont, who came up with the idea that carbon dioxide is a special kind of gas, distinct from air.

I am convinced that they will know more about the world in June than they did coming in, but, to be fair, that might just reflect a general maturity on their part.


I want my students to be wrong at least 5 times a class. At this point, I'll even except quiet wrongs, mistakes made on our old school whiteboards. I won't accept ludicrous wrongs unless there's a train of thought behind them.

One of the most important things I am just learning, now in my fifth year, that the truly ludicrous wrong answers have some thought or history behind them.

If a child hears over and over that photons are "particles" of light, well, then any rational child will think of light as "stuff." If a child hears over and over that plants make food from sunlight, it only confirms that light is "stuff." It's not, of course, but try unteaching this!

We spend a lot of class time unraveling bad science.

May is coming, the New Jersey Biology Competency Exam looms. Who has time for science? Trust me, lambs! Or else you will fail!


Ironically, van Helmont was a victim of faith and The Inquisition;
much of his work was not published in his lifetime, likely out of fear.

The cartoon is, of course, xkcd.

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