# Lesson 3

Contemos para sumar y restar

### Lesson Purpose

The purpose of this lesson is for students to use their knowledge of the count sequence to solve story problems involving adding or subtracting 1.

### Lesson Narrative

In previous units, students used objects and drawings to represent and solve Add To, Result Unknown and Take From, Result Unknown story problems. In this lesson, all of the story problems involve adding or subtracting one, which encourages students to use their knowledge of the count sequence to solve the story problems (MP7, MP8). Students may still choose to use objects or drawings to represent and solve story problems, which is great. In grade 1, students will build on this work as they relate counting to addition and subtraction.

If students need additional support with the concepts in this lesson, refer back to Unit 2, Section D and Unit 4, Section B in the curriculum materials.

• Action and Expression
• MLR8

Activity 2: Estudiantes que cantan

### Learning Goals

Teacher Facing

• Solve Add To, Result Unknown and Take From, Result Unknown story problems.
• Use knowledge of the count sequence to add and subtract one and determine one more and one less.

### Student Facing

• Resolvamos problemas-historia.

### Required Materials

Materials to Gather

### Required Preparation

Activity 3:

• Gather materials from:
• Less, Same, More
• Math Fingers
• Tower Build
• Math Stories
• Which One

Building Towards

### Lesson Timeline

 Warm-up 10 min Activity 1 10 min Activity 2 15 min Activity 3 15 min Lesson Synthesis 5 min Cool-down 5 min

### Teacher Reflection Questions

In the next lesson, students will determine one more and one less than a given number with no story problem context. How does the work of this lesson prepare students for that work?