An idea which can be used only once is a trick. If one can use it more than once it becomes a method.
George PolyaIf you wish to learn swimming you have to go into the water and if you wish to become a problem solver you have to solve problems.
George PolyaIt is better to solve one problem five different ways, than to solve five problems one way.
George PolyaIf the proof starts from axioms, distinguishes several cases, and takes thirteen lines in the text book ... it may give the youngsters the impression that mathematics consists in proving the most obvious things in the least obvious way.
George Polya