Tuesday, June 5, 2012

What insects need to live

One of the objectives of our second grade insects curriculum is that students should learn that insects need 4 things to live.

You know them, right? Quick! Name them!

I'm sure you got it right, but in case you didn't, here are the 4 things: food, water, air, and space.

In the past few years, we've started writing learning targets for our lessons, so that both the teachers and the students know what they are supposed to learn. One of our learning targets is this: "I can list what insects need to live." If you can list those 4 things, you get it right. If you can't, you have missed your target.

(We write more interesting learning targets than that one. But it is easiest to write and assess objectives that involve remembering facts, and hardest to write and assess objectives that involve thinking and analysis. This is one danger of objectives.)

A few weeks ago, in an inquiry group for science teachers, we took a deeper look at some student work having to do with this learning target. We looked at one student's observational drawing of a milkweed bug habitat, and we looked closely at partial transcripts of science discussions from two classrooms.

We noticed, when using the Collaborative Assessment Conference to look at the drawing, that while the student had painstakingly labeled, with arrows, the insects' food, water, and air holes, when she wrote the word "space," she drew an arrow pointing to the word "space" itself. Her label was pointing at itself.

This prompted us to think about how abstract "space" is. Who decided insects need space, anyway? What does that mean? Do they need a space to live in? Do they need just enough space for their bodies so they don't get squished? We began to eye our list of four needs with some suspicion.

In the science talk transcripts, the students dug deeply into the idea of what insects need to live. That's not what the discussions were intended to be about -- the teachers had asked where insects live. But as students shared ideas about where they live, they naturally started to talk about what they need to survive. They talked about food, and that insects live in places where they can get the kind of food they need. They talked about protection -- insects live under logs because it is dark and safe and hard to find them.

Then one student said that insects need each other to survive.

We, the teachers, thought hard about that. It made us wonder: What does "live" mean? Does it mean that an individual insect lives? Or does it mean that a species survives? If it's the latter, they most certainly do need each other. 

The second graders, though, weren't thinking about reproduction. They were thinking about safety. They were pretty sure that some insects protect each other. If that was the case, didn't those insects need each other to survive? (If you're not sure about this, check out this video of fire ants making a raft so they can survive a flood in the jungle.)

[The students in one class designed an experiment to see if insects need each other to live. They took one mealworm and put it, alone, in a habitat with food, water, air, and space. It died. The mealworms die easily, so this is hardly incontrovertible evidence, but the second graders were pretty convinced.]

The more we thought about it, the sillier this learning target seemed to us. Do the curriculum writers have any idea of the diversity of insects on earth? Those insects need very different kinds of things to live in very different places. What is really interesting about insects is how they live in certain places so they can get what they need to live -- an idea the students began discussing almost immediately. This seems like a Big Idea about insects (and all living things) that could lead to all kinds of thinking and analysis, instead of just memorizing four things that insects supposedly need to live. 

This is one of the many stories that make me think we should always word our objectives as questions, not as answers. What do insects need to live? There are many answers, and we could investigate them all year.