Excellent for our needs - a bright 4th grader ready to go further than school curriculum, but doesn't know everything already. Each section begins with clear explanation of a mathematical concept, leavened with commentary from a pair of non-intimidating cartoon characters. Then a brief instructional section clearly presents one or two useful strategies with examples worked out. At the end of the chapter are multiple sets of problems: Level 1, Level 2, and "Einstein" problems. Since they are not marked by grade level, you're not limited by expectations-- you just go as far as you are ready to go. Next year, we will cycle back through and tackle more of the harder problems. I worked through several sections with my son this summer and we both really got into it. Thanks!