Wednesday, September 3, 2008

First day of school, biology (sophomores)

First we went through the usual introductory ritual--see the previous post.

I brought a slug to school today. I saw him creeping on the stoop last night, and enticed him into a container with a pellet of fish food.

The first picture I show the class is a series of hominids representing human evolution. I ask if we descended from chimpanzees, listen to the answers, then gruffly announce no way we came from chimpanzees. (A few look puzzled, though I might get a smug look from a budding creationist--he's one of us.)

After a very brief statement that no biologists believe we descended from chimpanzees, everyone looks confused, even my smug co-conspirator.

We went through some more procedural nonsense, then I showed a photograph of a slug.
Hey, that's a slug!

"Yep," I agree, "Limax maximus. What can you tell by looking at the picture?"
Um, it's slow?

"Can you see that?"

A young woman, and one I suspect who will do well, notes that the slug in the picture is in some leaves, and that maybe it likes to eat them. Still, not much more to say. It's a picture. Can't see it move. Can't hear it. Can't even smell it. Eww....

I introduce my slug before the dust settles.

After assuring the class that it is alive, someone inevitably shouts out.
Pour salt on it
I don't, of course, and give my best teacher frown, but until the kids get to know my slug (or any slugs) a little better, they'd do just that.

The critter is a bit stunned. Too much light, too much motion, but I put his open container on a student's desk, and place a fish pellet nearby. I announce to the slug it's time to eat.

An eyestalk pops out, then another. It s-l-o-w-l-y slithers to the pellet, then more things pop out as its mouth wraps around the food.

"How did it know the food was there?"
It saw it!

Any other possibilities
It smelled it?

I agree both are possible, though I really don't know which answer is right.
"Maybe it heard me announce mealtime."

The kids are fascinated now. I ask what do they think would happen if they touch an eye?

A young woman does.

The critter immediately pulls in its eye stalks, and starts to push out the pellet. A couple of student gets upset that someone has touched the slug's eye stalk.
The same slug offered salt a few minutes earlier.

"Why did the slug pull in its eye stalk? Why did it spit out the pellet?"
Um, it didn't like it.

I ask the class what they would do if flicked in the eye while eating a sandwich. OK, a bit too much anthropomorphizing. Still, we discussed eating versus getting away when threatened. All this took place in 3 minutes.

I finish off by announcing that this slug has been evolving as long any other critter in the room. "We're distant cousins."

They don't laugh, a good sign. Or maybe I've already been labeled certifiable.

And the slug? Safely back home in the garden--I'll kidnap another one tonight for tomorrow's class.


Phoenix Rising said...

I love this account. I like to do demos like this that stress observation, but you fit so much in so little time with a slug, of all things. Neat.

doyle said...

Dear Phoenix Rising,

Thanks for your words--I've been wondering how to start the year in two weeks, and I may go back to this.

(I think I was originally planning to use a brown snake, but couldn't find one the night before. We're surrounded by them in Bloomfield, yet most kids in town have no idea.)