Title – Expressing Multiplication as Repeated Addition

By – Glenn Kagan

Primary Subject – Math

Grade Level – 3-5

In this lesson, you will learn how to express multiplication as repeated addition.

Step 1: Print and hand out a copy of a blank multiplication table.

Step 2: Explain to the students that after they do this investigation, they will copy their answers on this worksheet.

Step 3: For each multiplication fact (except for the 0 table), you will draw circles to "model" its repeated addition. Use the following definition to guide how to model each multiplication fact:

3 x 4 = 12

3 = a number

4 = how many sets of that number

12 = total or product

example:

o o o

o o o   =   3 + 3 + 3 + 3 = 12

o o o

o o o

Step 4: Review the definition above, and tell the students to use it as a guide for when you model each multiplication fact.

Step 5: After they finish, probably the next day, review the commutative property, and give them an example. Then explain to them that even if two facts might the same answer, they have different repeating additions. Here is an example of it:

3 x 4 = 12 ; 4 x 3 = 12

3 + 3 + 3 + 3; 4 + 4 + 4

Step 6: Ask a student to refer back at the definition, and explain why 3 x 4 is different from 4 x 3, in relation to the definition.

Step 7: To wrap things up, ask another student if he / she understands multiplication better, after the modeling and filling out a copy of the multiplication table, based on those results.

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Glenn Kagan

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