This Instructional Activity is a part of the Lesson 1, Unit 7, Grade 8. Students know that they can estimate the length of a side of a right triangle as a number between two integers and identify the integer to which the length is closest. It is important for students to understand that these irrational numbers can be approximated, but it is not yet necessary that they know the definition. Basic points should include the theorem, the converse of the theorem, and the fact that when the theorem leads them to an answer of the form of perfect squares.