This Instructional Activity is a part of the Lesson 8, Unit 8, Grade 8. The purpose of this activity is to give students practice finding missing side lengths in a right triangle using the Pythagorean Theorem. Arrange students in groups of 2. Give students 10 minutes of quiet work time and then have them compare with a partner. If partners disagree about any of their answers, ask them to explain their reasoning to one another until they reach agreement.