This Instructional Activity is a part of the Lesson 12, Unit 7, Grade 8. The large quantities involved in these questions lend themselves to arithmetic with powers of 10, giving students the opportunity to make use of scientific notation before it is formally introduced. This activity was designed so students could practice modeling skills such as identifying essential features of the problem and gathering the required information. Students use powers of 10 and the number line as tools to make it easier to calculate and interpret results. Notice the ways in which students use relevant information to answer the questions. Identify students who can explain why they are calculating with one operation rather than another.