In this lesson, the balance beam model for multiplication will be demonstrated using an actual balance beam. The best type to use is one with hanging weights, but you can modify the directions if you have only pan balances available by enclosing sets of weights in baggies.
Display a balance beam and review with children how it operates. Ask a volunteer to place 3 weights at position 2 of the left arm of the balance beam. Then ask, "Where would we need to place just 1 weight on the other side so that the beam balances?" Accept and try all student responses. When the correct response of 6 is given, ask students to record this using the equation 3 × 2 = 6. (If a balance scale is being used instead, this same demonstration can be completed by placing 3 baggies with 2 weights in each baggie on the left side of the pan balance; then, 6 baggies with 1 weight each can be used on the right side to create balance.)
Repeat these steps with other multiplication facts as necessary.
Students can also use the Pan Balance—Numbers applet to create multiplication numbers for a partner to solve.
For example, on one side of the pan balance, a student could enter 7 * 3, and the other student would type 21 on the other side. (Note: The applet requires the use of an asterisk (*) instead of × to indicate multiplication, because the standard keyboard does not include the times symbol.)
Next show children the Product Game. Then, play a sample game with them, using volunteers from the class.
As students work in pairs, they should find other multiplication equations with the balance beams or play the Product Game. Students can also use number facts (4 × 3 = 12, for example) to play a "paper version" of the Product Game.
Allow the students to use both electronic tools until the class period is nearly over. Then call them together to discuss the experiences they have had that day using the Questions For Students below.
