I'm a teacher too! A similar idea of mine led me to discover that the analog board attached to the CRT in the compact cases is a thoroughly unique little beast as far as frequencies and so on. It's not easily compatible with much else that sends a video signal without some serious electronic engineering.

People have successfully hacked in other 9" monochrome monitors, or used the electronic guts of an Apple 12" monochrome monitor attached to the 9" tube.

Personally I'm going the 9" monochrome SVGA guts way.

Look at the first few pages of Hacks forum topics. I found lots of (discouraging) info there.