Briney Dave said :

Native tanks sound pretty cool but I think that it may be too much of a risk to ok kids going out and netting fish in streams.

I'll come and help you net some.  I'm about a hundredth as knowledgeable as Todd, but I have all the gear, including ID books and watershed maps.  And I have one thing Todd doesn't:  Time!

pundam said :

Boy, I had the wrong science teachers. Where were all of you when I was coming up?

Absolutely!  Dave's the Best, and he has the Teacher of the Year award to prove it! 

Dave, I think your class might enjoy Crystal Red/Black Shrimp if you want to learn about breeding certain traits. They come in varying grades (and are priced accordingly). You can start with low grades and selectively breed the higher grade offspring, or vice-versa. Take your pick. Really neat. That is how the pure white, or as the breeders are calling it "Golden", Crystal Red came about. Low grade you're looking $3-$7 each. Higher $10-$50. There is also a black variety.

There are also people breeding blue and purple Tiger Shrimp with different eye colors (gold being the most desireable).

You can also do the same thing, to a lesser degree, with the lowly Red Cherry Shrimp and selectively breed out the most red ones. They are cheap to get also, about $1 each.

Edit: Doh, forgot classes are only 9 months. You may want to skip that Crystal Reds then. They breed much slower than the Red Cherry Shrimp, which breed like cockroaches. Ask MO about that.

A planted tank would be cool. That's much easier to do in a 9 month period, to compare the different substrates and so forth. 10g tanks with one or two strip lights, HOB filter. Simple, cheap, easy.

I like the live food thing that Scott suggested. Helps the kids learn and great fish/coral food!

Hey Dave- what size are the tanks? I seem to remember they were in the 10 to 20L size.

Breeding some shell-dwelling cichlids might be interesting, and not take up too much space. Maybe some other sort of dwarf cichlid as well.

Killifish? Goodieds? Other endangered livebearers? If Susan and I ( and possibly others ) go to the Detroit auction, we could possibly pick up some interesting stock for a few bucks ( plants as well ).

An interesting project that would requrie two tanks would be to have them both under the same strip light, and have one with the clay/sand/gravel substrate, and one with ugf and gravel. Plant them both, and compare at the end of the season. Having a breeding set of guppies in each, you could count the fish at the end to compare carrying capacity.