The document describes several early classroom technologies in chronological order: the hornbook from 1650 which displayed the alphabet on wood or bone protected by horn; the magic lantern from 1870 which projected images from glass plates in dark rooms; chalkboards from 1890 which were initially made of slate or painted wood; the Analytical Engine from 1830, an early general-purpose computer designed by Charles Babbage; and the Difference Engine from 1820, an automatic mechanical calculator also designed by Babbage to calculate polynomial functions.