# Lesson 2

Problemas-historia y ecuaciones

### Lesson Purpose

The purpose of this lesson is to solve Add To and Take From, Result Unknown story problems, write an addition or subtraction equation to represent each story problem, and orally explain how the equation represents the story problem.

### Lesson Narrative

The work of this lesson connects to the previous lesson in which students represented and solved Add To and Take From, Result Unknown problems in any way they chose and wrote expressions to represent the problems. In this lesson, students write equations to match story problems, drawing a box around the result. The first activity provides an opportunity for students to make sense of stories in which the addends and results are provided, and write an equation to match. Students consider how the actions in the story problem relate to the equations they wrote. In the second activity, students represent and solve story problems, writing equations to match. In the lesson synthesis, students are asked to relate an equation with an unknown to a story problem.

The problems in this lesson continue with the library context used in the previous lesson. Consider taking photographs or the school library or a library in your community to share with students.

• Representation
• MLR6

### Learning Goals

Teacher Facing

• Solve Add To and Take From, Result Unknown problems.
• Write addition or subtraction equations to represent a story problem and orally explain why it matches.

### Student Facing

• Resolvamos problemas-historia y escribamos ecuaciones.

### Required Materials

Materials to Gather

Building Towards

### Lesson Timeline

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

### Teacher Reflection Questions

As students worked in their partnerships and small groups today, whose ideas were heard, valued, and accepted? Is there a norm that could be added to encourage students to include all group members in discussions?