Sunday, December 11, 2011

Teaching photosynthesis

I work hard to make my classroom "unscientifical." I discovered not so long ago that some students learn just enough scientifical vocabulary to throw me off their scent.

We are raising a generation of liturgists. I ask specific questions no one truly understands, I get back scientifical nonsense no one understands, and everyone pretends something was learned.
Teacher Priest: What is ATP?
Student Congregation: ATP is the main energy currency of cells.
I bet I can teach a parrot the Krebs cycle.

Light is light, and stuff is stuff, and never shall the twain meet. (Well, not in the Newtonian universe, anyway.)

Photosynthesis does not turn light into food. Yet almost all my lambs believe this. I suspect they believe this because that's what they've been told. It explains, logically, how trees can get so big without creating a crater around them.

Photosynthesis, of course, bangs together the atoms of CO2 and H2O to form a bigger, far less stable organic molecule. (We pretend that it's glucose, but it's really not... we simply cannot tell even simple truths to children.)

I am an educational professional--I can train most children to "know" the photosynthesis equation:

CO2 + H2O → C6H12O6 + O2

I can train the same students the respiration equation:
C6H12O6 + O2  → CO2 + H2O

And yet when I combust an organic compound, they are dumbstruck that water--the kind that comes out of faucets--"comes out" of the reaction, not internalizing that H2O is indeed the same thing as, well, water.

I don't want to be an educational professional. I want to be a teacher.

So tomorrow I light up the propane torch once again, and show them water from "fire." We'll discuss fire and energy and stuff.

I'll shine a bright light through my homemade chloroplast solution--just let some spinach leaves sit in alcohol for an hour or two--and let the children see the transparent green solution fluoresce an opaque deep red, as though transformed into blood, and we'll talk about excited electrons bouncing up, then back down. What is light? What is energy?

And they'll leave the class confused, because they'll think what they saw is magic.

It's not magic; I will not allow magic in my classroom. Magical thinking destroys our connections to the earth. We owe it to children to tell the truth.

I don't want to be an educational professional. I just want to teach.

The skeleton photo was right before my first back to school night ever!


Sue VanHattum said...

>It's not magic; I will not allow magic in my classroom. Magical thinking destroys our connections to the earth.

I have a problem with this. I think you and I mean different things by the phrase 'magical thinking'. But that's part of the problem I have. The common definition of the word magic kind of defines it out of existence.

I'm having trouble thinking of a way to write about what I mean by magic. Thinking about it, I think of 2 or 3 times in my life, and two stories from other people. It takes an essay, not a comment, to explain... Here's what I wrote about it before.

Can you tell me what you mean by 'magical thinking', and why you don't like it? Seems to me what you're unhappy with is your lambs trust of authority.

doyle said...

Dear Sue,

Good morning!

Science is based on observing the natural world--since I teach science, I try (as much as possible) to keep my room free of "magic," although we do have a class leprechaun. As I constantly remind my charges, I may howl at the full moon while dressed in robes for all they know. I keep any magic I might practice strictly outside.

By "magical thinking" I mean thinking that things can happen just because you wish them so. I realize major (and minor) religious institutions do just that, but it's no way to run a government and it's no way to live on a planet with limited resources.

I've got my idiosyncrasies--we all do--but emphasizing our connection to the natural world (upon which science rests) is not so common anymore.

Just to be clear, I do not mean that many things happen that our beyond our current understanding, and that some things will never be understood, nor that basing one's life focused on the natural world's phenomena is the way to live.

It is, however, the only way I know how to understand the world.

Sue VanHattum said...

Good morning to you, Michael!

Starhawk (who I write about in my post) is so with you.

What you're describing in your post is how students think they know something because they have words and images to 'explain' it. Real knowing is deeper than that, and (in science) comes from observation of the natural world. I get that part. I just wouldn't call what your students are doing 'magical thinking'.

In math real understanding comes from following the logical steps from one thing that must be true to another.

I don't think I ever understood the problem with the way science is taught until I began reading your blog. I kinda liked learning about the Krebs cycle in my high school biology class. That teacher had us dissecting and observing, but I sure don't remember anything I observed.

What I remember best from dissection is how skin is barely connected to the body. It's like clothing. That was a surprise to me.

Tom Hoffman said...

I always wondered about what was so special about ATP, and if I asked I don't think I got a satisfactory answer. It always seemed like some kind of magical molecule.

doyle said...

Dear Tom,

ATP is a special molecule like your "nervous" aunt is a special human. Its specialness comes from its instability. The 3rd phosphate is hanging in there like a dart on a cheap toy dart gun.

And like your special aunt, when it lets go of the phosphate, it destabilizes other molecules.

(Yeah, a cheap explanation--maybe I'll post about ATP to help me get a better handle as well.)

Kathryn J said...

I feel the same way teaching atomic structure to my students this week. I am asking them to understand that what they perceive as solid is mostly empty space and the force fields are what makes it appear "solid". I am teaching that all of color is electrons flip-flopping up and down the energy levels in something that they will never see or touch.

I do science magic in which we do flame tests and copper always burns bright green, lithium bright red, etc. We look at spectral tubes through diffraction gratings and they see lines.

Yet - their math abilities, level of understanding, and depth of curriculum means that they must accept these things I tell them as truth without verifying them independently. Some are fascinated, some struggle, some clearly don't care - the anticipated announcement from CERN tomorrow about something the media has dubbed the "god particle" doesn't mean much to them.

But, if I can get them interested and lay down a foundation on which they can build... Maybe someday, they will be pushing the limits of our understanding.

Kathryn J said...
This comment has been removed by the author.
Holly said...

"ATP is a special molecule like your "nervous" aunt is a special human. Its specialness comes from its instability. The 3rd phosphate is hanging in there like a dart on a cheap toy dart gun."

Interestingly enough, my fellow biology teacher and I actually use a toy dart gun when talking about ATP.

I've found (thanks to the same colleague) that "skits" seem to really help the students understand photosynthesis and cellular respiration better. It's not perfect because they still try to memorize everything without really processing it, but it works decently.

Would like to hear more about how you show them combustion and water coming out of the reaction. We discussed it (our book mentions car combustion and burning a marshmallow--water coming out of a burning marshmallow really confused them), but I suspect they just smiled and nodded.

doyle said...

Dear Kathryn,

I fire up a propane torch and aim it at the faucet stem--the metal stem sweats.

I then challenge the kids to figure out what it is.

(Sometimes I use glassware with ice, but I need a whole set up then for safety reasons--shield, goggles, etc.--and I often forget to bring the ice. The faucet stem is sitting right there.)

Occasionally I'll breate on the faucet stm so that they can see that whatever comes out of the torch looks and feels exactly the same as what comes out of our breath. I can then just walk over to the faucet, and it bangs back the memory of the torch.

It can take months for the kids to accept that water result from combustion. It's contrary to the universe already constructed in their heads.

doyle said...

Or maybe that last one should be to Holly--the Google has muddled up who siad what....

Anonymous said...

I thoroughly enjoyed reading your blog! I edit school science textbooks and it gets a bit monotonous after a while. Reading your blog was a refreshing breath of very welcome CHANGE! Thank you!

Anonymous said...

If you fancy a song to teach your students to help with the basics of photosynthesis, then you can use one I wrote and have put on youtube. Thankyou!: