Multiplication Strategies: Using Doubling
The Flip Flop Multiplication Decks are a great way to strengthen students’ conceptual understanding of multiplication and to introduce the strategies for solving the basic multiplication facts. The set includes nine different decks. There are 36 cards in each deck with 4 categories including numerals, dot groups, dot arrays, and multiplication facts as well as 8 additional Zapp! cards and 9 blank cards.
To see the Flip Flop Multiplication Decks click here, or go to the PRODUCTS page.
When students are learning their basic multiplication facts, four strategies that use the “doubling” concept are:
- Doubling when learning the facts with a factor of 2
- Doubling and adding one more set when learning the facts with a factor of 3
- Doubling and doubling again when learning the facts with a factor of 4
- Halving then doubling when one of the factors is even
The cards in the decks show the group model and the array model as a visual representation of the facts. These cards can be used in the following ways to teach the “doubling” strategies.
1. Activity for doubling and adding one more set: Use the group and array cards that show 3 groups/rows of a number to discuss doubling and adding one more set. Use a screen (cover) to screen the third set or row. Have the students solve it without seeing the third set. Ask how they solved it.
2. Activity for doubling and doubling again: Use the group and array cards that show 4 groups/rows of a number to discuss doubling and doubling again. Give the students a toothpick. Ask them to show half the items by separating the items in half with the toothpick. Have them figure out the total of half. Then have them double that. Ask how they solved it.
A variation of this activity would be to screen or cover 2 of the sets or rows. Have the students double the first two sets. Then ask them to double that amount.
3. Activity for halving then doubling: Use the group and array cards that show 4 groups/rows of a number, 6 groups/rows of a number, or 8 groups/rows of a number. Have the students divide the groups or rows in half with a toothpick. Have them solve the half first and then double it.
After students have explored these strategies conceptually using the visual models, then pair the expression with the visual models and guide the students to make the connection with the expression. See if they can transfer the strategy to the expression.
I was working with a group of students recently on the doubling strategies. After doing a variety of these activities with the students, I had them choose an expression card and explain how they solved it. It was exciting to hear them explain orally as well as show in writing how they used the strategies we had been working on.