This Instructional Activity is a part of the Lesson 7, Unit 1, Grade 6. In earlier lessons, students saw that a square can be decomposed into two identical isosceles right triangles. They concluded that the area of each of those triangles is half of the area of the square. They used this observation to determine the area of composite regions. This activity helps students see that parallelograms other than squares can also be decomposed into two identical triangles by drawing a diagonal.