# Lesson 9

Todos los problemas-historia

### Lesson Purpose

The purpose of this lesson is for students to solve addition and subtraction story problems.

### Lesson Narrative

In a previous unit, students solved Add To, Result Unknown and Take From, Result Unknown story problems. In previous lessons, students solved Put Together, Total Unknown and Put Together/Take Apart, Both Addends Unknown story problems. In this lesson, students solve familiar types of story problems. Because the types of story problems are mixed, students need to make sense of what the story is asking them to do (MP1). Then, students create their own story problem.

• Representation
• MLR7

### Learning Goals

Teacher Facing

• Solve addition and subtraction story problems.

### Student Facing

• Resolvamos problemas-historia.

### Required Materials

Materials to Gather

### Required Preparation

Activity 3:

• Gather materials from:
• What’s Behind My Back, Stage 1
• 5-frames, Stages 1 and 2
• Make or Break Apart Numbers, Stage 1
• Math Stories, Stages 1–3

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 15 min Activity 3 15 min Lesson Synthesis 5 min Cool-down 0 min

### Teacher Reflection Questions

Unlike talking, listening is a difficult thing to observe. At what points in the lesson did you observe students listening to one another’s ideas today in class? What indicators do you have that they were listening?