Lesson 13

The purpose of this lesson is for students to solve problems involving multiplication within 100, where one factor is a teen number, in a way that makes sense to them.

The work of this lesson connects to previous work because students have used strategies to multiply one-digit factors. Now, they have the opportunity to extend these strategies to the multiplication of teen numbers. Students may use area diagrams and expressions to represent multiplication strategies, which they used in the previous section. Students solve problems involving the multiplication of teen numbers, then make a poster of their work with a student who solved in a similar way. During the gallery walk, students see a variety of ways to represent and solve the problem (MP2). This will be helpful in the next lesson where students make sense of specific representations of multiplying within 100 when one factor is a teen number.

Which students had opportunities to share their diagrams and thinking during whole-class discussion? How did you select these students?