In this lesson, students practice finding the area of the region between rectangles when one is contained by the other. In the associated Algebra 1 lesson, students create frames around rectangular regions and explore the area of the frame. By first exploring the area of the region between two rectangles, students will be prepared to use quadratic equations to represent the area of the frames they create.

The Estimation Warm-up gives students the opportunity to make sense of a problem (MP1) involving rectangles. Students look for and express regularity in repeated reasoning (MP8) when they find the area of rectangles and create expressions with variables to represent the area between two rectangles. They also reason abstractly and quantitatively (MP2) when they interpret the situations into drawings and expressions.