Since we’re focusing on the life sciences this year I want to complete the nature trail. Part of this project is to catalog the biodiversity on the trail. I’d like to have students specialize on the different types of organisms we find. Undoubtedly, the Class Insecta will be well represented. The site, Entomology for Beginners is a great basic resource. It starts with very simple cartoons of insect parts but also has a great key to insect orders which walks you through the comparisons you need to make to identify the Orders in which a particular insect belongs.
The site also has a page on simulating the dynamics of insect populations using a simple model. This may be for the more advanced student however.
A more general guide to bugs (Phylum Arthropoda) can be found at Bug Guide. Their Clickable Guide to the left of the page is a great starting place.
Luc Viatour has a large gallery of macro images of members of the Phylum Arthropoda.