# Lesson 4

Does the Number Change?

### Lesson Purpose

The purpose of this lesson is for students to count collections of objects and understand that the number of objects in a collection stays the same, regardless of how they are arranged.

### Lesson Narrative

Students will count the same collection of objects in different arrangements to build this conservation of number, which develops through experience over time. While developing conservation of number, students may need to recount the objects each time they are rearranged. With repeated practice, some students may know that the number of objects is that same without recounting (MP8). The purpose of the lesson synthesis is to highlight that a collection of objects does not need to be counted when they are rearranged.

- Action and Expression

- MLR8

Activity 2: Count, Rearrange, Recount

### Learning Goals

Teacher Facing

- Answer “how many” questions about groups of up to 20 objects
- Know that counting a group of objects will yield the same number, regardless of their arrangement or how they are counted.

### Student Facing

- Let’s figure out how many objects there are when the objects are moved around.

### Required Materials

Materials to Gather

- 10-frames
- Collections of objects
- Connecting cubes
- Counting mats
- Materials from a previous activity
- Materials from previous centers

Materials to Copy

- Number Mat 1-10

### Required Preparation

Activity 1:

- Each student needs a collection of 11–20 objects.

Activity 2:

- Each student needs a collection of 11–20 objects.

Activity 3:

- Create a tower with 16 cubes for the activity synthesis.
- Gather materials from:
- Find the Pair, Stage 1
- Number Race, Stages 1 and 2
- Subtraction Towers, Stage 1
- 5-frames, Stages 1 and 2

### CCSS Standards

Addressing

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 10 min |

Activity 2 | 15 min |

Activity 3 | 20 min |

Lesson Synthesis | 5 min |

Cool-down | 0 min |

### Teacher Reflection Questions

As students worked together today, where did you see evidence of the mathematical community established over the course of the school year?