Curriculum  /  Math  /  2nd Grade  /  Unit 7: Working with Even, Odd, and Equal Groups  /  Lesson 8

Working with Even, Odd, and Equal Groups

Lesson 8

Math

Unit 7

2nd Grade

Lesson 8 of 12

Objective

Build and represent various arrays with the same total.

Student-Facing

I can build and represent various arrays with the same total.

Common Core Standards

Core Standards

  • 2.OA.C.4 — Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and up to 5 columns; write an equation to express the total as a sum of equal addends.

Foundational Standards

  • 1.OA.D.7

Criteria for Success

  1. Understand that an array is made up of equal rows and equal columns. 
  2. Represent totals in different array forms, such as arranging a total of 12 counters into 4 rows of 3 as well as 2 rows of 6.
  3. Represent the total number of objects in an array as a repeated addition equation in terms of columns or rows.

Tips for Teachers

In this lesson, students will represent arrays in more than one way and see that the totals remain the same even if the rows and columns are organized with different amounts. This goes beyond the commutative property, where students might read an array of 3 rows of 4 as 4 columns of 3 but see that the 12 counters can also be rearranged into an array of 2 rows of 6. Push students to think about arrays by organizing their thinking around the columns and rows, not just one or the other. So, for example, if discussing the array of 2 rows of 6, they should also be able to describe the same array as 6 columns of 2.

Lesson Materials

  • Two-sided counters (25 per student)

Warm Up

5-10 minutes

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Anchor Tasks

15-25 minutes

Problem 1

Choose the two repeated addition expressions that match each array.

a.   

  1. A.   2 + 2 + 2

  2. B.   2 + 2

  3. C.   3 + 3 + 3

  4. D.   3 + 3 

b.   

  1. A.   3 + 3 + 3 + 3

  2. B.   4 + 4 + 4 + 4

  3. C.   4 + 4 + 4

  4. D.   3 + 3 + 3

c.   

  1. A.   5 + 5

  2. B.   5 + 5 + 5

  3. C.   3 + 3 + 3 + 3 + 3

  4. D.   2 + 2 + 2 + 2 + 2

Purpose

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Problem 2

Sean and his family wanted to plant 20 green bean plants in an array with rows and columns.

a.   What are two different ways they could arrange the plants in an array? Draw a model with circles to represent each plant.

b.   Write a repeated addition equation to represent the total for each of your two arrays.

Purpose

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Problem Set

15-20 minutes

Target Task

5-10 minutes

Here is a group of counters.

a.   Draw an array with equal groups to represent the counters shown.

b.   Write a repeated addition equation to represent the total.

Student Response

Additional Practice

Daily Word Problems, Warm Ups, and Center Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Next

Use concrete squares to build rectangles.

Lesson 9
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Even and Odd Numbers

Topic B: Composing and Analyzing Arrays

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