I know this has come up in the past, but I had a real world reminder of it this past weekend. DS8 and I went to visit my sister and her son, who is 9 and in third grade. I asked him how school was going and he said it was great. He went on to tell me very excitedly that he would be learning multiplication soon and that they just started fractions. So I asked him what he knew about fractions - to which he answered "we only started learning about them on Thursday" OOPS! I actually did the same thing last year when he said he might be learning multiplication in second grade - I asked him "quick, what is 2 x 2" and got the same "we haven't learned it yet" response.
What a concept - my nephew doesn't know about a subject before they begin to teach it in school. Other than some spelling words and some social studies topics, I don't know if my DS has ever encountered that feeling of not knowing a subject before it was taught. (Which I guess is why he is often heard saying he would really like school if he learned something there.)
