# Lesson 10

Suma y resta con una decena

### Lesson Purpose

The purpose of this lesson is for students to find the value that makes an equation true when one value is a teen number and one is a ten.

### Lesson Narrative

In the previous lesson, students found the value that made addition equations true when one addend was 10. In this lesson, students find the missing value in story problems and addition and subtraction equations. They may find the missing value in any way that makes sense to them. In the syntheses, students discuss how the relationship between addition and subtraction is helpful when finding missing values.

- Action and Expression

- MLR6

### Learning Goals

Teacher Facing

- Find the value that makes an equation true where the total is a teen number.
- Use the relationship between addition and subtraction to find missing values.

### Student Facing

- Sumemos y restemos con números del 11 al 19.

### Required Materials

Materials to Gather

### Required Preparation

### CCSS Standards

Addressing

### 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

How did the student work you selected impact the direction of the discussion? What student work might you pick next time if you taught the lesson again?