This lesson includes several summative application activities. There are two optional activities that involve going outside or to a room with very high ceilings to indirectly measure a tall object. In the first optional activity, students use mirrors (or shallow bowls of water) and in the second, they choose their own tools (MP5). The time estimates given are for doing each activity separately. If students do both the mirror method and the alternate method on the same trip outside, the activities will take less time.

The other activity focuses on similar triangles and scale factors. Students explore the geometry of reflection angles when a ball is bounced off a wall, first estimating and then precisely calculating the path of the ball. They have a chance to reason abstractly and quantitatively (MP2) as they compare their estimated path with their calculated path, using similar triangles and the physics of reflection.

The activity "Bounce It In" works best when each student has access to devices that can run the applet because students will benefit from seeing the relationship in a dynamic way.