# Lesson 18

Ecuaciones con valores desconocidos

### Lesson Purpose

The purpose of this lesson is for students to interpret equations with a symbol for the unknown and connect them to story problems.

### Lesson Narrative

In the previous lesson, students compared different types of story problems. They solved story problems and wrote equations to match the problems. In this lesson, students work with a symbol for the unknown in an equation for the first time. A box is used for the unknown to build on the previous work in the unit where students put a box around the number in the equation that answered the question. In this lesson, students explain how their equation matches the story by relating it to the quantities and the unknown in the story problem.

- Representation

- MLR6

### Learning Goals

Teacher Facing

- Interpret equations with a symbol for the unknown in relation to story problems.
- Solve a variety of story problem types.

### Student Facing

- Demos sentido a las ecuaciones con cuadros vacíos.

### Required Materials

Materials to Gather

Materials to Copy

- Story Problem Cards Grade 1, Spanish
- Equation Cards Grade 1, Spanish

### Required Preparation

Activity 1:

- Create a set of Story Problem Cards and Equation Cards for each group of 2.

### 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

Reflect on how comfortable your students are asking questions of you and of each other. What can you do to encourage students to ask questions?

### 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 |