May I suggest skin on frame boats?

For example www.yostwerks.com has a lot of different free designs.

They are easy to build, you can avoid the toxic stuff like glassfiber and epoxy, materials are usually a fair bit cheaper, and you will end up with a sturdy lightweight boat.

There's also the advantage that you don't need a mold, so a class of 5 students can build 5 boats at the same time.

Check it out, and think it over. :)

http://yostwerks.com/DesignsMenuWood.html