I love to use Pentominoes in the math classroom. This is a 3-day activity. Day 1 the students learn what a pentomino is. They cut out all pentominoes that they can think of. Day 2 the students determine which pentomino nets will form a cube (without a lid). The trick is, they are NOT allowed to pick up and fold the nets. This is great practice with spacial relations. Day 3 the students are puzzling the pentominoes pieces together to form rectangles of certain dimensions.