Wanted to add that we have recently started reading Life of Fred Apples and my son is really enjoying it. We first tried it around age 3 and he didn't like it at all. Pulled it out on a whim this week and he is really enjoying the humor and he loves the math, even though he has known the math it in for a long while. I'm just happy he's enjoying it. He loves that Fred is a 5 year-old math professor.