CHICAGO — Before SMART boards and laptops, teachers used overhead projectors to make visuals for fidgeting students, marking black-lined transparencies with a felt-tipped marker. It wasn’t ...

The machine had something of religious instruction about it. A hush fell upon the classroom as we were thrown into darkness.

By not forcing a teacher to rely solely on books, a multimedia projector makes more educational information available to students. It changes conventional habits and rituals in the classroom. In fact, ...