This lesson invites students to practice the strategies they have used to find unknown lengths in similar right triangles. A key strategy for students to practice in this lesson is using proportional relationships within similar triangles to find unknown lengths in other triangles. In a subsequent unit students will study trigonometry through similar right triangles, and the ratios in trigonometry tables are ratios within triangles.

The Information Gap routine requires students to make sense of a problem by determining what information is necessary, and then to ask for the information they need to solve the problem. This may take several rounds of discussion if their first requests do not yield the information they need (MP1). It also allows them to refine the language they use and to ask increasingly more precise questions until they get the information they need (MP6).