# Lesson 3

Sumemos o restemos para resolver problemas-historia

### Lesson Purpose

The purpose of this lesson is for students to solve story problems involving addition and subtraction within 100 without composing or decomposing a ten.

### Lesson Narrative

In previous grades, students solved a variety of Add To, Take From, Put Together/Take Apart, and Compare problems. In previous lessons, students added and subtracted within 100 without composing or decomposing a ten using methods based on place value and the relationship between addition and subtraction.

In this lesson, students are invited to solve story problems and show their thinking or computations in whatever way makes sense to them. The activity and lesson syntheses focus on describing and connecting methods based on place value in preparation for upcoming lessons.

• Representation

### Learning Goals

Teacher Facing

• Describe their methods using place value understanding.
• Solve story problems involving addition and subtraction within 100 without composing or decomposing a ten.

### Student Facing

• Resolvamos problemas-historia.

### Required Materials

Materials to Gather

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 the first activity, students used the Three Reads routine to make sense of the problem. What strategies did you see students use to make sense of the story problems on their own? What questions did you ask to ensure students made connections between their representations, calculations, and the context of the stories?

### Suggested Centers

• Capture Squares (1–3), Stage 2: Subtract within 10 (Supporting)
• Five in a Row: Addition and Subtraction (1–2), Stage 5: Add within 100 without Composing (Supporting)