A few popular math books for school children are "Math Curse" by Jon Scieszka, "How Much Is a Million?" by David M. Schwartz and "The Grapes of Math" by Greg Tang, according to Goodreads, Inc. These books are for children ages 11 and under.
Some of the books on the list, such as "The Grapes of Math," also have an online version. In this case, Greg Tang offers an interactive ebook, where the user must answer a variety of math questions before moving to the next page; hints are provided for students who get stuck. Greg Tang also provides resources, such as games, study materials and other books for students from first to eight grade, as well as advanced problems for students who wished to be furthered challenged.