ABSTRACT
The days when a teacher had only his voice, a blackboard and chalk, and large sets of books to aid him in his work have long since passed. In current times he is faced with what can seem a bewildering range of aids of many kinds, with new ones constantly appearing on the market. This superabundance of aids offers teachers considerable opportunities to make their work more effective, to release them from some tasks and to provide variety and flexibility, but at the same time it can also cause some teachers to use aids just for the sake of using them or it can bewilder some teachers to such an extent that they use very few.
