# Lesson 3

Midamos en un mapa

### Lesson Purpose

The purpose of this lesson is for students to measure lengths in centimeters and add and subtract lengths within 20 to answer questions.

### Lesson Narrative

In this lesson, students add and subtract within 20 and build fluency within this range of numbers. They also practice measuring lengths in centimeters and use their measurements to add and subtract. The activities encourage students to consider ways to use properties of operations to make easier or known expressions and use the facts they know (MP7).

In the first activity, students measure lengths on a map and add and subtract their measurements to answer questions. They share the ways they used facts that they know to find the value of sums and differences. The questions focus on the measured distances in centimeters. It may be helpful to discuss how the actual distances between cities are much longer. However, proportional relationships, such as those in a map scale, is a grade 6 topic and should not be the focus of these activities. In the second activity, students solve Compare problems within the context of their measurements on the map.

The cool-down should be completed before the lesson synthesis so that students can share their responses during the lesson synthesis.

• Engagement
• MLR2

Activity 1: Midamos en el mapa

### Learning Goals

Teacher Facing

• Fluently add and subtract within 20.
• Measure lengths in standard units.

### Student Facing

• Sumemos y restemos medidas de longitud.

### Required Materials

Materials to Gather

Materials to Copy

• Measurement Map

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

In previous lessons, students found unknown addends and shared methods that included looking for ways to get to a ten to add and subtract. How did you see students use these methods in today’s lesson?