I use the cards to review before the unit test. I run them off on card stock then put each set of 24 in a plastic bag. Students are paired in groups of 2 or 3. They work together to solve each math problem on a slate, then they check their work with the teacher. If they are correct, they get one puzzle piece from their puzzle box. Once all 24 cards are solved and all 24 puzzle pieces are collected, students can then put together their puzzle.
*Puzzle pieces sold separately. I buy the 24 piece puzzles for $1 at the dollar store.