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.
Pan Balance— Shapes
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.
Rules for the Seven-Up Game
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.
