It may be more important in the mathematics class how you teach than what you teach.

If you cannot solve the proposed problem try to solve first some related problem.

There are many questions which fools can ask that wise men cannot answer.

I am intentionally avoiding the standard term which, by the way, did not exist in Euler's time. One of the ugliest outgrowths of the "new math" was the premature introduction of technical terms.

The world is anxious to admire that apex and culmination of modern mathematics: a theorem so perfectly general that no particular application of it is feasible.

One of the first and foremost duties of the teacher is not to give his students the impression that mathematical problems have little connection with each other, and no connection at all with anything else. We have a natural opportunity to investigate the connections of a problem when looking back at its solution.

It may be more important in the mathematics class how you teach than what you teach.