Here are a few tidbits:
Infancy: the sensory explorer - there are two segments, from birth to age three, and from age three to six.
Kids in this stage of life wonder what things are and want to do things by themselves. They're concrete thinkers, they live in the present, and are learning to make predictions about cause and effect. They love routines, repetition, and ground rules.
Childhood: the reasoning explorer - again, two phases, from ages six to nine, and nine to twelve.
Kids in this stage often ask "why" and often say "that's not fair." They can be ungracious, interested in clubs, and have a strong sense of moral justice and interest in good/evil.
Adolescence: the humanistic explorer - ages 12-15 and 15-18.
The favorite question is "How do I fit in?" and the favorite quotation is "Don't tell me what to do."
Growth and development accelerates again--it's comparable to the first three years of life the changes are so substantial. IQ literally drops as neurons are pruned and brains marinate in hormones. Kids this age are extremely sensitive to criticism and will rebel against authoritarians (moreso than just authority). They really want to make a memorable mark on the world.
Maturity - the doer: ages 18-21 and 21-24.
These people ask "Why am I here? How far can I go?" A favorite quotation: "What can I do?"
Physical growth is complete or nearly so. Impulse control/judgement development continues and they start to ask, "Is this a good idea?" There's a hunger for self-knowledge, self-understanding, self-realization, and they feel responsible to the world, though they need to overcome possessiveness, materialism and lust for power.
Lee made a great case that we can write books that will resonate with kids by understanding their emotional development at the level we're writing for.
"The more the child understands about himself, his potential, and his environment, the more he'll understand what his role in life can be," she said. "This means he'll be seeking to read about and identify with characters--fact or fiction--that are ready, as he is, to search, explore, challenge, and understand life--and make a memorable impact on it."