Opaque projector

A machine that projects written material directly onto a screen. Used simply by placing a book, or diagram in position under the high wattage camp and it is enlarged and projected onto a screen.[Advantages]

Mechanically simple and thus perhaps less liable to go wrong or to be misused.

[Disadvantages]

Tends to be heavy, cumbersome and slow to use. It needs a darkened room which can restrict note taking by participants.