# Lesson 18

Diagrams and Equations for Word Problems

### Lesson Purpose

The purpose of this lesson is for students to relate diagrams and equations to two-step word problems.

### Lesson Narrative

In grade 2, students interpreted tape diagrams for one- and two-step problems involving addition and subtraction. Earlier this year, they did the same with one-step word problems involving multiplication. They also learned that a question mark, a blank line, or a box could be used to represent an unknown quantity in an equation.

In this lesson, students connect tape diagrams and equations with a symbol standing for the unknown quantity to two-step word problems. The work of this lesson prepares students to write equations with a letter standing for the unknown quantity and solve two-step problems, using a diagram if it helps them.

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Relate diagrams and equations to two-step word problems.

### Student Facing

• Let’s connect diagrams and equations to situations.

### Required Materials

Materials to Gather

Materials to Copy

• Card Sort: Situations, Equations, and Diagrams

### Required Preparation

Activity 1:

• Create a set of cards from the blackline master for each group of 4.

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

Students previously used tape diagrams to represent and solve one-step addition, subtraction, and multiplication problems. How are they leveraging that knowledge in this lesson on two-step problems?

### Suggested Centers

• Tic Tac Round (3–5), Stage 1: Nearest Ten or Hundred (Addressing)
• Number Puzzles: Addition and Subtraction (1–4), Stage 5: Within 1,000 (Addressing)
• Five in a Row: Multiplication (3–5), Stage 2: Factors 1–9 (Supporting)