# Lesson 11

### Lesson Purpose

The purpose of this lesson is for students to add a two-digit number and a multiple of 10.

### Lesson Narrative

In previous lessons, students added and subtracted multiples of 10 from other multiples of 10. In this lesson, students reason about the value of expressions where both addends are two-digit numbers; one addend is a multiple of 10 and the other is not. Students use and explain methods that make sense to them and show what they understand about what the two digits in a two-digit number represent (MP3, MP7).

• Action and Expression
• MLR8

### Learning Goals

Teacher Facing

• Add a two-digit number and a multiple of 10.

### Student Facing

• Let’s add tens to two-digit numbers.

### 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 methods did your students use to add tens to two-digit numbers? Which methods surprised you, and which did you expect?

### Print Formatted Materials

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