This game has students work in groups of four. Each student is responsible for finding the perimeter of one of the shapes. They must add their 4 perimeters together and tell the teacher the SUM. If the sum is correct, they receive points. If their sum is incorrect, they have to work together as a group to figure out where they made the mistake.
I love this game because it holds student individually accountable while also encouraging collaboration is someone has a misconception in their thinking.
Shapes included are squares, rectangles, triangles, parallelograms, and trapezoids.