My kids just love these. They are great problems that help to prepare for standardized tests when they get older. The questions are interesting, challenging, yet read in a way that the kids can follow and enjoy them. this is one of the few books where they actually ask to 'play'. That should say a lot. I highly recommend, along with some of the others in the Perplexors series. I would say this is for 1st-3rd grade.