Oli - I would not worry about over or under doing it. When my ds was 4 he wanted to know and do everything solar system. He would ask me so many questions to which I did not know the answers that I would secretly cry out of frustration. Bc he learns without repetition I had to be very careful not to give him the wrong answer. I went with it though. I followed his lead and spent many hours in the library getting strange looks from people bc my kid was talking about the universe, black holes and supernovas. I took him to planetariums and did other related activities well beyond his age bc I knew he would be interested. I've always believed learning should be fun and never followed a script. Leap frog is great - ignore the age rating and go with your gut.
I encourage IQ testing around age 4 if only to help you advocate for your daughter's needs in the school system (if she's going to attend school in the US).
Best of luck!
Last edited by FrustratedNJMOM; 08/01/09 02:59 AM.