# Lesson 15

Grupos iguales, números más grandes

### Lesson Purpose

The purpose of this lesson is for students to multiply within 100, where one factor is a teen number.

### Lesson Narrative

The work of this lesson connects to previous work because students have seen a variety of ways to represent and solve problems in which one of the factors is a teen number. In this lesson students use their choice of strategy and representation to solve these types of problems. Students participate in a gallery walk to highlight different ways that they solved problems with a synthesis that highlights the area diagram to represent one of the problems. Students’ attention is drawn to scaling of area diagrams during the warm-up. While it’s not important that student representations are exact, it is important that any area diagrams presented to students are to scale.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Multiply within 100, where one factor is a teen number.

### Student Facing

• Resolvamos algunos problemas de grupos iguales que tienen números más grandes.

### Required Materials

Materials to Gather

Materials to Copy

• Centimeter Grid Paper - Standard

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 20 min Activity 2 15 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

What question do you wish you had asked today? When and why should you have asked it?

### Suggested Centers

• Compare (1–5), Stage 3: Multiply within 100 (Addressing)
• How Close? (1–5), Stage 5: Multiply to 100 (Addressing)