At times, it can be a bit of a challenge to steer kids away from the IPOD and such....on a whim, we bought a simple field microscope before a recent camping trip.
We got this:
http://www.amazon.com/Carson-Micro-Brite-Pocket-Microscope/dp/B000Z3A8UY/ref=pd_sbs_sg_5
It is a simple, cheep kids...