# Lesson 18

Contemos problemas-historia a partir de expresiones (optional)

### Lesson Purpose

The purpose of this lesson is for students to create story problems to match expressions and fill in expressions to match story problems.

### Lesson Narrative

This lesson is optional because it does not address any new mathematical content standards. This lesson does provide students with an opportunity to apply precursor skills of mathematical modeling. Throughout the unit, students have acted out, told, and solved story problems and interpreted and found the value of expressions. In this lesson, students apply their understanding of story problems and expressions to create story problems that match a given expression. In the second activity, students share their story problems and other students figure out which expression they were making a story problem for. When students make choices and translate mathematics back into the context of a real world situation, they model with mathematics (MP4).

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Create a story problem that matches a given expression.
• Fill in an expression to match a story problem.

### Student Facing

• Contemos problemas-historia que correspondan a expresiones.

### Required Materials

Materials to Gather

### Required Preparation

Activity 3:

• Gather materials from:
• Find the Value of Expressions, Stage 1
• Roll and Add, Stages 1 and 2
• Shake and Spill, Stages 1-3
• Number Race, Stage 1
• Math Stories, Stages 1 and 2

### Lesson Timeline

 Warm-up 10 min Activity 1 10 min Activity 2 20 min Activity 3 15 min Lesson Synthesis 5 min Cool-down 0 min

### Teacher Reflection Questions

As you finish up this unit, reflect on the norms and activities that have supported each student in learning math. List ways you have seen each student grow as a young mathematician throughout this work. List ways you have seen yourself grow as a teacher. What will you continue to do and what will you improve upon in the next unit?