begin the lesson, ask students what an addition sentence or addition
equation looks like. They might respond with, 9 + 7 = 16. Students
should notice there are two addends, the addition symbol, the equal
symbol, and a sum. Students may share other examples, as necessary.
Introduce the Pan Balance - Numbers Tool to the students.
Put 4 onto the left pan by typing in the red space above the pan. Ask students, "What happens? Why?"
Now put 9 onto the blue right pan by typing in the space above the pan. Ask students, "What happens? Why?"
Note: These two steps help introduce students to the mechanics of the electronic tool.
Next, pose the following scenario to students:
What number sentences can you create using the number 12?
First reset the balance. Put 12 into the right pan. Now put a sum
(two numbers added together) onto the left pan that will balance with
12. Ask students why the pan balanced.
Next, show another sum that balances with 12. Ask students,
"How many sums can you find?" Students may indicate the following sums:
0 + 12
1 + 11
2 + 10
3 + 9
4 + 8
5 + 7
6 + 6
This would also be an appropriate time to review the commutative property of addition, namely 3 + 9 has the same sum as 9 + 3.
Next put 3 + 9 on the left pan. Put something onto the right pan
that will make it balance. Then find something else that will balance
with 3 + 9. Ask students, "Why does this work? How many answers can you
find?" Students may indicate the following sums:
7 + 5
6 + 6
and so on...
As necessary, share more examples with the class. When you have
finished the whole-class demonstration and exploration, students should
work in pairs to use the the Pan Balance - Numbers Tool.
Distribute the Addition Equations activity sheet to each pair of students.
Students should work together to complete the five activities on the activity sheet.