Nor are they people who cannot afford a compact disk player.
Using remote control, a teacher can order a disk player to find and display still or moving images of a particular subject.
About seven million compact disk players have been sold since 1983, the year they were introduced.
The industry leaders hope that as more disks are produced, school districts will buy disk players to play them.
None of the three companies are yet buying cars with compact disk players.
By 1989, the number had grown to 17.3 million disk players, the association says.
Today the price of a disk player has come down to about $400.
Several excellent compact disk players now list at $299 and often sell for less.
Industry figures for 1991 show almost 850,000 disk players in use, up from about 650,000 in 1990.
I have seen a small disk player by the same maker.