Everything is On Sale

This Instructional Activity is a part of the Lesson 15, Unit 3, Grade 6. In this activity, students are asked to find 80% of several different values, generalize their process, and express their generalization in different ways. As they make repeated calculations, students look for and express regularity in their work and see more explicitly that P% of a number is P/100 times that number. Once they arrive at one or more generalizations, students practice articulating why each generalization always works.