Section C: Practice Problems Represent Multiplication with Arrays and the Commutative Property

Section Summary

Details

In this section, we learned how equal groups are related to arrays and how to represent arrays with expressions and equations.

drawing of equal groups

array

expression

equation

We also learned that we can multiply numbers in any order and get the same product.

Problem 1 (Lesson 16)

  1. Explain or show 2 different ways that you see equal groups in the array.

    Array. 3 rows of 6 dots.

  2. Arrange the dots in an array in a different way.

Problem 2 (Lesson 17)

Rearrange the circles to make an array in two different ways.

A group of 12 dots.

Problem 3 (Lesson 18)

There are 4 rows of water bottles in the box. There are 5 bottles in each row.

Draw an array representing the situation. Then, write a multiplication expression representing the number of water bottles.

Problem 4 (Lesson 19)

There are 5 rows of chairs in the room. There are 4 chairs in each row. How many chairs are in the room?

  1. Write a multiplication equation to represent the situation.

  2. Find the value that makes your equation true.

Problem 5 (Lesson 20)

  1. Write a multiplication equation that represents each array.

    1
    an array.
    2
    an array.

  2. How are the arrays the same? How are they different?

Problem 6 (Exploration)

Andre says that there are an odd number of circles in this picture.

Do you agree with Andre? Explain or show your reasoning.

5 rows of circles. First row, 1 circle. Second row, 2 circles. Third row, 3 circles. Fourth row, 4 circles. Fifth row, 5 circles.

Problem 7 (Exploration)

Find a collection of objects in the classroom or at home that is arranged in an array.

  1. Describe the objects.

  2. Create a drawing of the objects.

  3. Write an equation showing how many objects there are.