# Lesson 8

Count Columns and Objects in Columns

### Lesson Purpose

The purpose of this lesson is for students to see that in an array of objects, the objects are arranged into columns with an equal number of objects in each column.

### Lesson Narrative

In the previous lesson, students learned that an array is an arrangement of objects into rows with an equal number of objects in each row.

In this lesson, students refine their understanding of an array to include the fact that the objects in a row are equally spaced from each other. When arranged this way, the objects also line up into columns. Students use mathematical language to describe arrays and recognize that rows go side to side and columns go up and down (MP6). They use the structure of the array to find the total number of objects in an array (MP7).

Students should have access to counters throughout the lesson, including during the cool-down.

- Representation

### Learning Goals

Teacher Facing

- Describe an array as an arrangement of objects into columns with an equal number of objects in each column.

### Student Facing

- Let’s learn about columns in arrays.

### Required Materials

Materials to Gather

### Required Preparation

Activity 2:

- Each student needs 25 counters.

### 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

Outside of class, how can you reinforce the array work done today? Are there opportunities at other times during the day to ask students to represent or count objects using an array?

### Suggested Centers

- Write Numbers (1–2), Stage 4: Skip Count by 2, 5, and 10 (Addressing)
- Target Numbers (1–5), Stage 7: Subtract Hundreds, Tens, or Ones (Supporting)