Dr. Quine has some great ideas. I would also add a slide-out keyboard to the bottom of the tablet, much like what is already used on the Motorola Droid and some other manufacturers' cell phone designs to maximize the user input functionality (and increase screen space). This would also help decrease some of the screen fingerprints.
The killer hardware solution for touchscreens would be to figure out how to avoid fingerprints, dirt, and scratches on the display. Some plastic screen protectors and careful wiping make it possible to keep iPhone screens clean - but the challenge multiplies for an iPad or computer. Why not display a virtual image so that the "touch screen" would be in the air and the finger position would be detected by a camera without ever touching a physical surface?
The devices should be military-hardened if they are expected to survive the 8-10 year old group, especially if they leave the classroom.
Now, in the classroom, they still need to be a bit more durable than the existing ones, if they are to be practical, especially with current budget cuts that are so prevalent in today's educational systems.
Personally, I think money can be better spent on our educators than popular devices.