# Lesson 18

Todas las maneras de formar 10 (optional)

### Lesson Purpose

### Lesson Narrative

In a previous unit, students found more than one solution to Put Together/Take Apart, Both Addends Unknown story problems. In a previous lesson, students used objects, images, and equations to make and break apart 10.

In this lesson, students solve a Put Together/Take Apart, Both Addends Unknown story problem with a total of 10. Then students work together to find all of the solutions to a Put Together/Take Apart, Both Addends Unknown story problem with a total of 10. Students may notice patterns in the solutions, such as that when one addend increases the other addend decreases, to help them determine if they have found all of the solutions. This lesson is optional because the standards do not require students to find all of the solutions for Put Together/Take Apart, Both Addends Unknown story problems.

If students need additional support with the concepts in this lesson, refer back to Unit 5, Section C in the curriculum materials.

- Action and Expression

- MLR8

### Learning Goals

Teacher Facing

- Compose and decompose 10 in multiple ways.

### Student Facing

- Encontremos todas las maneras de formar 10.

### Required Materials

### Required Preparation

Activity 1:

- Students can use their bead tool from a previous lesson.

Activity 2:

- Students can use their bead tool from a previous lesson.
- Create a chart displaying solutions to be used during the lesson synthesis.
pigeons in the

fountainpigeons on the

bench9

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Activity 3:

- Gather materials from:
- Shake and Spill
- Number Race
- Grab and Count
- What's Behind My Back?
- Pattern Blocks

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 10 min |

Activity 2 | 10 min |

Activity 3 | 20 min |

Lesson Synthesis | 5 min |

Cool-down | 5 min |