This Instructional Activity is a part of the Lesson 12, Unit 1, Grade 8. Have students complete Exercises 6-8 independently or in small groups. Allow time for groups to discuss their choice of unit and the reasoning for choosing it. Suppose you are researching atomic diameters and find that credible sources provided the diameters of five different atoms as shown in the table below. What new unit might you introduce in order to discuss the differences in diameter measurements?