# Teaching with Portals

Portal 2 is a game where you have to use portal guns to create teleportation fields to move around and survive. I’ve head about teachers using it for lessons, especially for physics, but I haven’t had the chance to look into it. There is a website teachwithportals.com which has lesson plans for use with Portal 2. Surprisingly with Language Arts lessons as well as science. I’ll have to look into this.

# Population counting

My 6th grade classes have started ecology, and this section is on determining how many organisms are in a population. As a warm up for the section, each table had 2 beakers, one filled with dry beans. They also had a ruler. They had 2 minutes to estimate how many beans they had. The trick was that they couldn’t just count them. They had to estimate.

The kids came up with varying methods of estimating. One of the better ones being to count how many beans you can put in a layer, then seeing how many layers there were and multiplying. One group was only off by 2.

This was a good introduction to some of the ways of counting populations.

1. Direct Observation Just count them all. Not always feasible.
2. Indirect Observation Frequently you can’t count the organisms, but you can count the signs of them. For example, you can count how many bird families are in a tree by counting the nests.
3. Sampling If the population is homogeneously spread, you can overlay a grid, and count how many in one grid square, then multiply to get the final estimate.
4. Mark and Recapture Sometimes ecologists carefully capture a group of organisms and mark them (tags, paint). Then they release them back to the wild. Later they capture more organisms, and count how many of them are marked. Then a simple formula tells the population size.

# Density and the Titanic

Had a good talk with my 6th grade period about density; I really didn’t expect to talk for the whole period about it, but it went really well. We talked about why you (hopefully) float in water. Then defined density and measured the density of a rock. This helped the kids understand why they sink.

But the fun part was towards the end. I brought up buoyancy, and one student made the connection to the Titanic. That as it filled with water its density changed. Eventually its density tipped over to greater than 1.0 and it sunk. That was a great connection. Then I talked about boats that are supposed to sink: submarines. How they can change their density by using the ballast tanks. The kids were pretty interested the whole time.