# 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:

### 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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Student Task Statements | docx | |

Lesson Cover Page | docx | |

Cool Down | Log In | |

Teacher Guide | Log In | |

Teacher Presentation Materials | docx | |

Blackline Masters | zip |