In this lesson, the balance model for addition will be demonstrated using an actual balance beam or pan balance. If you use a balance beam, you will hang weights from positions in the arms; if you use a pan balance, you will need to enclose sets of weights in plastic bags (and you may want to write on the bags the amount of weights in each). To use a balance beam, display it and review
with the students how it operates. Then ask a volunteer to hang a weight on the “3” position of the left arm of the balance beam and then another weight from the “2” position. Next ask “Where would we need to place a weight on the other side so that the beam balances?” If you use a pan balance and weights in plastic bags, put a bag with three weights and a bag with two weights on the left side
and ask how many loose weights would be needed to balance them. Accept and model all student responses. When the response “5” is given, ask students to record this using the equation 3 + 2 = 5. Continue with other weights until the children are comfortable with the process.
You may wish to introduce the children to the online Pan Balance - Shapes Tool as another way to practice.
When they have had time to explore, suggest that they write a portfolio entry about how a balance can help them find sums. Note that because the shapes have different values, when using the online balance, only one shape weight should be used throughout the session.
Next put the children into pairs and give them a set of Double 6 dominoes to share equally between themselves.
Have them place their dominoes upside down so that the spots are not visible.
Explain the rules of the “seven-up
game:”
- Each player turns over one domino and finds the total number of spots on it.
- If it is 7, the domino is placed on end on that player’s side of the desk and the player who turned it over writes the appropriate equation.
- If the domino has any other sum, it is removed from the pile.
- Then once all the dominoes have been turned over, the player who turned over the most dominoes with a sum of 7 lines up his or her dominoes and pushes them to make them fall over.
You may wish to display the Rules for the Seven Up Game Overhead so students have them handy.
Allow the students to play the Seven Up Game until the class period is nearly over. Then call them together to discuss their experiences using the following, or other, guiding questions.
