
Objectives
CCSS Math/Operations & Algebraic Thinking
 3.OA.A.1: Interpret the products of whole numbers, e.g., interpret 5 x 7 as the total number of objects in 5 groups of 7 objects each. For example, describe a context in which a total number of objects can be expressed as 5 x 7.
 3.OA.A.2: Interpret wholenumber quotients of whole numbers, e.g., interpret 56 ÷ 8 as the number of objects in each share when 56 objects are partitioned equally into 8 shares, or as a number of shares when 56 objects are partitioned into equal shares of 8 objects each. For example, describe a context in which a number of shares or a number of groups can be expressed as 56 ÷ 8.
 3.OA.A.3: Use multiplication and division within 100 to solve word problems in situations involving equal groups, arrays and measurement quantities, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.


Materials Needed


Introduction
Read aloud One Hundred Hungry Ants by Elinor Pinczes.


Procedure
 Pair students with a partner and tell them that they are going to explore different ways to show large groups of numbers so that the numbers are easier to count.
 Give each pair of students a set of 100 ant counters (or raisins). Ask the students to arrange their counters in arrays that were shown in the story: 2 groups of 50, 4 groups of 25, 10 groups of 10 and so on.
 Demonstrate that these groupings represent multiplication equations, such as 2 x 50 = 100, 4 x 25 = 100 or 10 x 10 = 100.
 Ask students to work together to find another way to represent 100 (e.g., 5 groups of 20 or 20 groups of 5). What multiplication equation does this arrangement represent? (5 x 20 = 100 or 20 x 5 = 100)
 Point out that they can also easily solve related division problems. For example, if we know that 2 groups of 10 equal 20, then we know that 20 ÷ 2 = 10. Similarly, if we know that 4 groups of 5 equal 20, then we know that 20 ÷ 5 = 4.


Guided Practice
 Give students a copy of the Ants Go Marching multiplication page and their own set of counters (or raisins).
 Challenge students to arrange 24 “ants” into an array.
 Then have them write the multiplication problem that corresponds to the array.
 Now challenge students to organize the ants to make two more different arrays. (For example, the student with 24 counters may arrange her counters in 4 rows of 6.) Be sure they understand that these arrays represent multiplication problems, such as 3 x 8 = 24 and 4 x 6 = 24.
 Point out that division is a natural extension of multiplication. Since we know 3 x 8 = 24, we also know 24 ÷ 8 = 3 and 24 ÷ 3 = 8.
 Ask students to complete the Ants Go Marching multiplication page by finding arrays for 48 and writing the corresponding multiplication problem.


Independent Practice
 Place a set of multiplication activity cards and a set of counters in a learning center.
 Challenge students to select a card and solve the question by using the counters to make a visual representation of the word problem, array or equation.


View the 3rd–5th grade lesson plan. (Includes all printable materials.)
