Lesson 14

Write and Solve Equations with Unknowns

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

  • Let’s work with equations with unknown numbers.

Required Materials

Materials to Copy

  • Card Sort Unknown Numbers

Required Preparation

Activity 1:

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

CCSS Standards

Addressing

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)

Print Formatted Materials

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Additional Resources

Google Slides

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PowerPoint Slides

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