This Instructional Activity is a part of the Lesson 18, Unit 7, Grade 8. Students complete Exercises 1-5 in pairs or small groups. These problems are applications of the Pythagorean theorem and are an opportunity to remind students of Mathematical Practice 1: Make sense of problems and persevere in solving them. Students should compare their solutions and solution methods in their pairs, small groups, and as a class. If necessary, remind students that we are finding lengths, which means we need only consider the positive square root of a number. Exercises 1.