Every biology class should have one.
We are currently wrestling with photosynthesis, akin to grappling with God and alchemy when we approach science as Show&Tell, which is how most of us approach "science" in a system that requires "objective" evidence that my lambs "know" what the state standards demand.
Sounds like catechism to me.
***The air you breathe out differs a little from the air you breathe in. Either way, it's still mostly nitrogen and oxygen. Though the expired air has over 100 times more carbon dioxide than what you take in, it's still mostly nitrogen and oxygen.
The pictures above reflect what kids are taught in elementary school--it is not wrong, but it is misleading.
The carbon dioxide you breathe out does not come from the oxygen you breathe in--it comes from the food you eat. Most of the mass (or "stuff") you lose when
The oxygen given off by plants does not come from the carbon dioxide they take in--it comes from water. The oxygen you use leaves your body as water.
And, for the love of Newton, plants do not convert sunshine into food. Sunlight is energy, and food is matter (or stuff)--in the Newtonian universe of high school biology, energy is energy and stuff is stuff.
Jan Baptist van Helmont was a nutty Flemish mystical alchemist who married rich, affording him time to dabble in all kinds of things back in the 17th century, even managing to get himself convicted during the Inquisition. He believed water and air could be transformed into just about anything, and set up a crude experiment to show that trees were made essentially of water.
The tree gained 164 pounds, the soil only lost 2 ounces, and van Helmont concluded, reasonably, that the tree gained its mass by transforming water. That's science--not great science, Mythbusters run better experiments--but still science. A testable hypothesis was made, the experiment run, data collected, and a reasonable conclusion was made.
And what do we do in class? We tell the van Helmont story, then tell the kids he was (mostly) wrong, something less tangible than water makes up the ash tree being passed around the room. Some write this down, some don't. No experiments will be run, no time.
Van Helmont was interrogated and confined by the Spanish Inquisition for challenging catechism, spending years under house arrest for daring to question the catechism of his day. I wonder what he'd think of a nation of science teachers now presenting his work as catechism, in order to meet the demands of our own inquisition, testing madness sponsored by the DFER, Achieve, Pearson, and Arne and his wealthy cronies.
A lot of us teach a lot of catechism--it's easier than teaching science, pays just as well, takes much less time, and keeps those who treasure test scores over truth out of our lives.
Arne and company believe that creating a nation of little scientists will improve our nation's economy, but he's wrong. Creating a nation of little abbot consumers might, and we're headed that way, but if my students had the time to truly see how the natural world works, how we are tied to the ground, how all living things face immutable limits, I bet they'd spend more time mulling than malling.
A fellow science teacher gave the ash tree to me--it served as the setting for a wedding he attended.
Van Helmont did not realize that most of a tree's mass comes CO2 in the air, ironic given that van Helmont is credited with discovering that very same gas.