16. The approval or disapproval of a group of boys and girls often brings about a very rapid change in physical, moral, or mental habits on the part of individual children. Why? 17. Why should drill work be discontinued when children grow tired and cease to concentrate their attention? 18. Why should reviews be undertaken at the beginning of a year's work? How can reviews be organized to best advantage during the year? 19. What provision do you make in your work to guard against lapses? * * * * * V. HOW TO MEMORIZE There is no sharp distinction between habit and memory. Both are governed by the general laws of association. They shade off into each other, and what one might call habit another with equal reason might call memory. Their likenesses are greater than their differences. However, there is some reason for treating the topic of association under these two heads. The term memory has been used by different writers to mean at least four different types of association. It has been used to refer to the presence of mental images; to refer to the consciousness of a feeling or event as belonging to one's own past experience; to refer to the presence of connections between situation and motor response; and to refer to the ability to recall the appropriate response to a particular situation. The last meaning of the term is the one which will be used here. The mere flow of imagery is not memory, and it matters little whether the appropriate response be accompanied by the time element and the personal element or not. In fact, most of the remembering which is done in daily life lacks these two elements. Memory then is the recall of the appropriate response in a given situation. It differs from habit in that the responses referred to are more often mental rather than motor; in that it is less automatic, more purposeful. The fact that the elements involved are so largely mental makes it true that the given fact is usually found to have several connections and the given situation to be connected with many facts. Which particular one will be "appropriate" will depend on all sorts of subtle factors, hence the need of the control of the connection aeries by a purpose and the diminishing of the element of automaticity. As was said before, there is no hard and fast line of division between habit and memory. The recall of the "sqrt(64)" or of how to spell "home" or of the French for "table" might be called either or both. All that was said in the discussion of habit applies to memory.