I live in a state with mandatory seatbelt laws. As a driver, if I get stopped and my passengers are unbuckled, I could lose my license. The questionable nature of such a law aside, anyone who would ask me to risk that kind of legal trouble because they don't feel like using a perfectly simple safety device can drive their own car.

My high school did this with students in 11th and 12th grades, except without the option to buy the machine at graduation. There were no restrictions in place, and I'm not aware of any problems that ever occurred because of it. However, that may become a different story when you put them in the hands of 6th graders. At the same time, the inability to install software or use iChat makes them mostly useless. In my experience, students often found useful software (besides games) to install and iChat became a very useful tool for collaborative work. As for web filtering, I recognize the legal requirement for it on school networks, but making it follow the machine everywhere will last until an enterprising student figures out how to get the filtering software off.

Although there is a practical limit to how far a single electron can go, electrical signals don't consist of a single electron going from one end of the wire to the other. Instead, it's like a game of miniature billiards, with electrons lined up in the wire. You pop one in one end, and another falls out the other end almost instantaneously.

The law doesn't actually force the states into making the drinking age 21. As is usual, when Congress anticipates the "that's unconstitutional!" outcry, they, rather than mandate it, make some funding conditional upon it. So, federal interstate highway funding in your state is conditional upon the 21 drinking age and the 0.08% legal limit of intoxication. But the federal government didn't "mandate" it. Neat trick, huh?