CrossNumber™ Math Puzzles: Sums encourages extensive use of mental arithmetic and estimation and requires students to produce different problem-solving strategies. Solutions require deductive reasoning and a conceptual approach to computation.

Puzzles in this series reinforce the commutative and associative properties of addition and the relationship between addition and subtraction.

Puzzles in the A, B, and C levels are increasingly difficult. The non-graded format enables teachers to have students work at ability, rather than grade level. Each page is self-explanatory and reproducible for single-classroom use