19. In general, use in your studying the form of activity that will later be demanded when the material is used.
You will use your knowledge of spelling ninety-nine times in a hundred in the writing of words in sentences. In accordance, then, with this rule it would be better to learn your spelling by writing the words than by learning them merely orally; in fact, it would probably be still better to learn them by writing them in actual sentences than to learn them merely by writing them in lists or columns. Young pupils need to know their multiplication tables for use in actual arithmetical work: it follows that these tables will be really learned only when they can be used in actual problems. Teachers are often surprised to discover that pupils who have learned the multiplication tables fairly well as tables still cannot multiply rapidly and accurately when they try to solve examples. Again, conversational French or German is to be employed presumably in talking: let it be learned aloud, then, rather than by silently perusing a textbook or by writing dozens of French or German sentences from dictation. Similarly, students who sometimes complain that they "know that stuff but can't answer questions on it" would do well to do their reviewing of it by asking themselves questions about it and practising the giving of answers.
20. Give most time and attention to the weak points in your knowledge or technique.
This rule seems almost too obvious to mention,
