Students will use problem solving to first solve the tetra decagon puzzle (using tangrams). This introduces the students to complex shapes. Once they know what shapes make up the tetra decagon, they will find the area of each shape. This will help them to solve the area of the tetra decagon. Next, students will find the perimeter of the complex shape. Not only are the students practicing area and perimeter, but they have to measure the shapes and choose the appropriate formula!