This Problem Set is a part of the Lesson 13, Unit 4, Grade 3. In this lesson, students use two strategies to find the area of composite shapes. First, they learn the "break apart" strategy, in which they find the separate the shape into two rectangles and add their areas. Then they learn to see a composite shape as a larger rectangle with part of the area cut out; by subtracting the area of the smaller "cut out" rectangle from the area of the larger rectangle, they find the area of the composite shape.