Decades of research has shown ...

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.
 David Elkind

Quotes from the same author

Children in the 21st (century) have been transformed from net producers of their own toy and play culture, to net consumers of play culture imposed by adults.
 David Elkind
Young children learn in a different manner from that of older children and adults, yet we can teach them many things if we adapt our materials and mode of instruction to their level of ability. But we miseducate young children when we assume that their learning abilities are comparable to those of older children and that they can be taught with materials and with the same instructional procedures appropriate to school-age children.
 David Elkind
It makes little sense to spend a month teaching decimal fractions to fourth-grade pupils when they can be taught in a week, and better understood and retained, by sixth-grade students. Child-centeredness does not mean lack of rigor or standards; it does mean finding the best match between curricula and children's developing interests and abilities.
 David Elkind
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.
 David Elkind
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.
 David Elkind