a bright idea. The questions and suggestions we are going to discuss tend to provoke such an idea.
In order to be able to see the student’s position, the teacher should think of his own experience, of his difficulties and successes in solving problems.
We know, of course, that it is hard to have a good idea if we have little knowledge of the subject, and impossible to have it if we have no knowledge. Good ideas are based on past experience and formerly acquired knowledge. Mere remembering is not enough for a good idea, but we cannot have any good idea without recollecting some pertinent facts; materials alone are not enough for constructing a house but we cannot construct a house without collecting the necessary materials. The materials necessary for solving a mathematical problem are certain relevant items of our formerly acquired mathematical knowledge, as formerly solved problems, or formerly proved theorems. Thus, itis oftenappropriate to start the work with the question: Do you know a related problem?
The difficulty is that there are usually too many problems which are somewhat related to our present problem, that is, have some point incommonwithit. How canwe choose the one, or the few, whichare reallyuseful? There is a suggestionthat puts our finger onanessential commonpoint: Look at the unknown!And try to think of a familiar problem having the same or a similar unknown.
If we succeed in recalling a formerly solved problem which is closely related to our present problem, we are lucky. We should try to deserve such luck; we may deserve it by exploiting it. Here is a problem related to yours and solved before. Could you use it?
The foregoing questions, well understood and seriously considered, very often help to start the righttrainofideas;buttheycannothelp always, theycannotworkmagic.