Anybody remember the movie "Computer wore tennis shoes?" In this movie the computer lent to the school for their computer training was a room-sized mainframe. By the time I went to high school, the computer we were lucky enough to have was about the size of a PC but so expensive we all had to share it.
Look at how far we have come. Raspberry Pi makes a credit-card sized computer that costs only $35. They have sold one million of these units to schools for teaching computer science students.
Read this NY Times article for more details. The power is turned on by plugging in the cable. The memory is supplied by a camera-style S card. And most people spring an extra ten bucks for the plastic protective case. But it does its job quite well and, most importantly, can teach kids how to use computers for very little money.