# Lesson 14

Escribamos y resolvamos ecuaciones con números desconocidos

### Lesson Purpose

The purpose of this lesson is for students to relate equations to and write equations for multiplication situations and diagrams using a symbol for the unknown number.

### Lesson Narrative

Students have worked with addition and subtraction equations with a symbol to represent the unknown number in grades 1 and 2. Students build on that work and the work with multiplication equations in the previous lesson as they encounter multiplication equations that have a symbol for the unknown number for the first time.

• Representation
• MLR8

### Learning Goals

Teacher Facing

• Relate equations to multiplication situations and diagrams using a symbol for the unknown number.
• Write equations for multiplication situations and diagrams using a symbol for the unknown number.

### Student Facing

• Trabajemos con ecuaciones que tienen números desconocidos.

### Required Materials

Materials to Copy

• Card Sort Unknown Numbers, Spanish

### Required Preparation

Activity 1:

Create a set of cards from the blackline master for each group of 2.

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

How do tape diagrams help students make sense of equations in which the unknown number is in different positions?

### Suggested Centers

• Capture Squares (1–3), Stage 5: Multiply with 2, 5, and 10 (Addressing)
• Five in a Row: Addition and Subtraction (1–2), Stage 8: Add within 1,000 with Composing (Supporting)