These 'principles of learning' can also be taken for the 'principles of teaching,'. . .

1. Active learning. . . The best way to learn anything is to discover it by yourself. . . What you have been obliged to discover by yourself leaves a path in your mind which you can use again when the need arises.
2. Best Motivation. . . For efficient learning, the learner should be interested in the material to be learnt and find pleasure in the activity of learning.
3, Consecutive Phases. . . Learning begins with action and perception, proceeds from thence to words and concepts, and should end in desirable mental habits. . . Let us distinguish three phases: the phases of exploration, formalization, and assimilation.

A first exploratory phase is closer in action and perception and moves on a more intuive, more heuristic level.
A second formalizing phase ascends to a more conceptual level, introducing terminology, definitions, proofs.
The phase of assimilation comes last: there should be an attempt to perceive the 'inner ground' of things, the material learnt should be mentally digested, absorbed into the system of knowledge, into the whole mental outlook of the learner. p. 607-608

    by George Polya     in (June-July 1963). On learning, teaching, and learning teaching. American Mathematical Monthly.