It's interesting to have some scientific evidence for one of Maria Montessori's significant contributions to educational theory - the idea of "sensitive periods.":
What happens if the "right stimulation is not available when the brain is ready for it? Are there certain times when the brain is more open to certain kinds of experience? When, if ever, is it too late to learn specific skills? Some of the most eye-opening research on neural plasticity shows that there are "critical", "sensitive," or "optimal" periods for some types of mental development. But if the right stimulus isn't available...too bad.
"In development it is now well known that there are certain times when an organism is ready to deal with certain stimuli," states Dr. Jane Holmes Bernstein. "And when those stimuli do not appear at the critical time, then it is likely that the brain structures that would have mediated them will not function and will die."
Both animal and human data support this real-life phenomenon of use it or lose it.
It sounds terrifying to think that some brain structures die if they aren't stimulated at the right time. How do we avoid such a catastrophe? Honestly, I think reasonably attentive parenting covers this almost automatically if these drives aren't suppressed by too much passive entertainment. Nature even forces it quite a bit. Consider a two year old. They're known as the terrible twos for a good reason. "I want DIS. What is DAT? Me do! Me do!" No, we can't always say yes, and we can't be available even for every learning opportunity. But a little appreciation of the value of those learning opportunities that two years olds are constantly bringing to us can be a really good thing!
Though I get tired too (believe me!), this has been one of my favorite "ages", since the years in which I spent lots of time with my young nieces and nephews when I was in high school (I had six nieces and nephews by the time I left for college and homeschooling allowed me to spend quite a bit of time with their families). It's so fascinating to watch their language and understanding of the world develop. I've always loved their funny ways of pronouncing things and their enthusiasm for "ordinary things" is wonderfully contagious - if we're not in too much of a hurry all the time. They can literally help you see the world in a whole new way. I'll never forget how one particular nephew spoke in single-syllable words for awhile (he's 19 now). He called me "Vlee" and a very enthusiastic sentence would run something like: "Look, Vlee, Moon!!!"
John and I are currently raising our sixth two year old and my opinion hasn't changed much. Maybe Frank drives me a little more crazy than some of the earlier toddlers since we've got more going on now and he IS a really active kid. This guy speaks loud AND carries a BIG stick! Wrestling and hitting things are some of his favorite occupations. Lots of supervision and intervention are required.
It seems to me that nature (by design!) forces lots of adult interaction at this extremely important stage. They're exploring everything (did I mention that Frank can open all the baby locks in the kitchen and unlock doors upstairs with a Q-tip?) and learning a ton about language and acceptable behavior. Frank repeats a lot of what he hears, but is starting to make some interesting connections too. The "Why you doin' dat?" question doesn't come up as much as it did only quite recently, but he instantly asks "why?" when we tell him no about anything. He doesn't like being read to very much yet, but he adores picture books: pointing at things and attempting their names and being asked to find a particular animal on the page and things like that. With this kind of interaction, he'll stay captivated for half an hour to an hour, despite his extremely high activity level (particularly if he's allowed to roll around at the same time).
Last night we were looking at a picture book about farms that had lots of great photos of animals, tractors and food (this one's a REAL winner!). Though I couldn't understand many of the words, he was telling a whole story with babbling and pointing about a harvester and something coming out the big spout - I think some of it had to do with going faster and going to the store.
Anyway, my point is that these "sensitive periods" for learning (critical in the early years) tend to be tackled naturally by parents and siblings through observation (children show signs of their need for learning), willingness to spend time interacting with them, and necessity - they'll drive you crazy with requests to fulfill this need. Reminds me of a great Chesterton quote Nancy Brown shared awhile back...
"Because children have abounding vitality, because they are in spirit fierce and free, therefore they want things repeated and unchanged. They always say 'do it again'; and the grown up person does it again until he is nearly dead. For grown up people are not strong enough to exult in monotony. But perhaps God is strong enough to exult in monotony. It is possible that God says every morning 'do it again' to the sun; and every evening 'do it again' to the moon."