Decades of research has shown that play is crucial to physical, intellectual, and social-emotiona l development at all ages. This is especially true of the purest form of play: the unstructured, self-motivated, imaginative, independent kind, where children initiate their own games and even invent their own rules.

I believe the important thing is to continue to create new experiences. That's why so many retired people travel. New experiences raise our consciousness and stimulate cognition. Retirement offers the opportunity to learn new things, and that is what keeps you young, at heart at least.

The idea of childhood as a social invention, in retrospect, is hardly credible. In the Bible, in writings of the Greeks and Romans, and in the works of the first great educator of the modern era, Comenius, children were recognized as being both different from adults and different from one another with respect to their stages of development. To be sure, the scientific study of children and the increased length of life in modern times have enhanced our understanding of age differences, but they have always been acknowledged.

Preschoolers sound much brighter and more knowledgeable than they really are, which is why so many parents and grandparents are sosure their progeny are gifted and super-bright. Because children's questions sound so mature and sophisticated, we are tempted to answer them at a level of abstraction far beyond the child's level of comprehension. That is a temptation we should resist.

The shift from the perception of the child as innocent to the perception of the child as competent has greatly increased the demands on contemporary children for maturity, for participating in competitive sports, for early academic achievement, and for protecting themselves against adults who might do them harm. While children might be able to cope with any one of those demands taken singly, taken together they often exceed children's adaptive capacity.

Friendships in childhood are usually a matter of chance, whereas in adolescence they are most often a matter of choice.

Certainly, young children can begin to practice making letters and numbers and solving problems, but this should be done without workbooks. Young children need to learn initiative, autonomy, industry, and competence before they learn that answers can be right or wrong.