Designing software to maximize learning

I take it as axiomatic that those involved in developing educational software intend that it should maximize learning. The evaluation of educational software, therefore, needs to focus mainly on this central issue. There are still, however, two ways in which 'maximization&' can be measured: either in terms of the increase in the amount of learning, or in terms of the increase in the quality of learning. In either case, an important contributory factor in the evaluation of educational software is the amount of take-up in terms of purchase and use.