In previous units, students learned to use the standard algorithm to multiply multi-digit numbers and practiced using it in prior lessons. In this lesson, students reason about how the factors in a problem can influence the multiplication strategy they use. They recognize that the standard algorithm can be more useful in some cases than others. Each activity launches with an opportunity for students to review the problems before solving and the syntheses focus on student reasoning about their choices. It is important to note that there is not one correct strategy for each problem. If students need additional support with the concepts in this lesson, refer back to Unit 4, Section A in the curriculum materials.

Through teaching, we have the opportunity to learn about our own understandings as well as those of students. What is one thing you learned today about your own understandings, and what is one thing you learned about the understandings of students?