The Science Wide Open books are considered appropriate for children from 4 to 8 years old, and the science discussed in the books is applicable to children up to 12 years old. The My First Science Textbook series is geared toward ages 2-6, but are great for children of all ages, as they have content from the first month or so of a chemistry course condensed into something a young kid can understand. (Even toddlers can get into chemistry with our board books.)