Teaching aids.

A teaching aid is exactly what it says it is--an aid to teaching. No matter how exciting the aid may be, its production is not an end in itself, merely a means to an end. Teaching aids are most effective and can be best justified when a need for them has been demonstrated and when they can be shown to clarify the teaching of points and problems which students have formerly found difficult to understand. The best teaching aids are the result of a combination of imagination and enthusiasm. Aids should always be evaluated to determine whether the costs of production are justified by an improvement in learning.