As a matter of fact, the adaptability of a program to changes in its objectives (often called maintainability) and to challenges in its environment in terms of the degree to which it is neatly structured.

But active programming consists of the design of new programs, rather than contemplation of old programs.

Clearly, programming courses should teach methods of design and construction, and the selected examples should be such that a gradual development can be nicely demonstrated.

During the process of stepwise refinement, a notation which is natural to the problem in hand should be used as long as possible.

Experience shows that the success of a programming course critically depends on the choice of these examples.

In the practical world of computing, it is rather uncommon that a program, once it performs correctly and satisfactorily, remains unchanged forever.

Programming is usually taught by examples.