Our twins love love love these books. They really connect with the humorous presentation and irreverence, combined with clear and accurate content. We started with math and science back when they were 7ish (?) yo. We own most of the math and science series, and also some of the geography and history. They are now 11 yo and in middle school, and dd still picks them up for pleasure reading, even after having read them many times over the years. Enjoy!