Claudia Zaslavsky 
Number Sense and Nonsense [PDF ebook] 

More than 80 games and activities in this newly updated edition help kids ages 8 to 12 think critically about math instead of just memorizing rules. Group and individual games teach fun, useful ways to manipulate odd and even numbers, prime and composite numbers, common and decimal fractions, and factors, divisors and multiples of numbers. Counting, calculating and writing numbers in languages from other cultures, such as China and Egypt, provide more practice in understanding how numbers work. Riddles, puzzles, number tricks and calculator games boost estimating and computation skills for every math student.