I really think kindergarten, and most of first grade, is simply social. It's not academic, IMHO. I just had my kids read alot of advanced books at home and work 2 grade levels ahead on math with Kumon and Singapore Math during that period.
My younger one is in second grade now and he's way ahead of his class. He was way ahead in Kindy and first grade. He never seems to care though- he's very social and he doesn't seem to notice! Last week he said excitedly, "we learned to count by twos!" I told him, you learned that a long time ago. Well, he is happy, so... He can add and subtract 3 digit numbers and multiply two digit numbers; his teacher has no idea.
I don't think most teachers can really differentiate in the early grades alot. They have their hands full in the early grades- kids are learning how to sit still, hold their pencil, write their letters...
