But let's go with the ratio idea - take 3 hypothetical 6 year-olds with I.Q.s of 150, 100, and 50. One has a "mental" age of 9, one of 6, and one of 3. It seems to be that the 9 year-old and the 6 year-old are going to be closer in ability than the six year-old and the 3 year-old.
If we're only talking about mental age (i.e., we're leaving fine & gross motor skills out of it), I'm not sure I agree.
Take reading. A typical 3 year old will be learning pre-reading skills and a typical preschool classroom will be focused on basic skills like enjoying books and learning the alphabet song. A typical 6 year old will be learning to sound out simple words and a typical 1st grade classroom will be focused on decoding skills. A typical 9 year old will already be a fluent reader, and a typical 4th grade classroom will be much more focused on content. They are three distinct stages, and I am equally horrified at the thought of that ND 6 year old struggling to learn in a classroom of kids who are fluent readers as I am at the thought of a ND 3 year old struggling to learn in a classroom of kids who are already sounding out words. (Of course, the 3 year old is much more likely to be running around like a whirlwind than attempting to learn, but then we're getting into emotional/social age.
)
Just to be perfectly clear, I'm not invested in this idea. I'm really not sure what I think just yet.
