Here are some models I have made called 'slide-togethers' - they were devised by George Hart.  They are easy to make and give rigid, attractive models - and don't require glue - perfect for a classroom project!  (You can also create a large number of them using a laser-cutter if you have one)

There is also some interesting maths involved in their design. For example, in the triangle and square ones, the side lengths are divided in the golden ratio in order to give the pentagon/pentagram effects.  

If you consider the points where the slits meet as vertices, you can see how they are related to the Archimedean solids (apart from the star ones of course!).  I designed the one in the bottom right corner myself after looking at a (small) rhombicosidodecahedron.