Adding Three Numbers — Answer Key
Part A: Trace the Words
Trace each word carefully by following the dotted lines.
1. equal
2. same
3. swap
4. any
5. flip
6. group
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 2 + 3 + 4 = 9. So 4 + 3 + 2 = 9
The order of addends does not change the sum, a key Grade 1 property called the commutative property.
2. 1 + 5 + 2 = 8. So 5 + 2 + 1 = 8
Rearranging the numbers keeps the total equal because every addend still gets added in.
3. 6 + 2 + 1 = 9. So 1 + 2 + 6 = 9
First graders can check their work by reordering addends and confirming the sum stays the same.
4. 3 + 3 + 4 = 10. So 4 + 3 + 3 = 10
Even when numbers repeat, swapping their positions still gives the same total each time.
Part C: True or False?
Read each statement. Circle True or False.
1. 2 + 3 + 5 gives the same sum as 5 + 3 + 2.
True False
Changing the order of addends never changes the total, so both expressions equal the same number.
2. 4 + 1 + 2 is more than 2 + 1 + 4.
True False
They are equal, not greater, because both have the same three addends added together.
3. We can add 3 numbers in any order.
True False
Addition lets us group and swap addends freely, which is helpful when picking an easier pair to add first.