This Instructional Activity is a part of the Lesson 7, Unit 1, Grade 6. Previously, students decomposed quadrilaterals into two identical triangles. The work warmed them to the idea of a triangle as a half of a familiar quadrilateral. This activity prompts them to think the other way-to compose quadrilaterals using two identical triangles. It helps students see that two identical triangles of any kind can always be joined to produce a parallelogram. Both explorations prepare students to make connections between the area of a triangle and that of a parallelogram in the next lesson.