Adding Three Numbers — Answer Key
Part A: Trace the Words
Trace each word carefully by following the dotted lines.
1. start
2. count
3. next
4. jump
5. skip
6. more
Part B: Fill in the Blank
Write the missing word or number on each line.
1. Start at 4, count on 2 and 1. 4 + 2 + 1 = 7
Counting on from the largest number helps Grade 1 students add three numbers without recounting the first group.
2. Start at 5. Count on 3 and 1. 5 + 3 + 1 = 9
Beginning at 5 and counting up is faster than starting at 1 and adding every number one by one.
3. Start at 6. Count on 2 and 2. 6 + 2 + 2 = 10
Counting on two small groups after the biggest number keeps the jumps short and easy to track.
4. Start at 7. Count on 1 and 2. 7 + 1 + 2 = 10
Starting with the largest addend means fewer steps, which helps first graders avoid losing count.
Part C: True or False?
Read each statement. Circle True or False.
1. To count on, we should start at the biggest number.
True False
Starting big means the fewest counting-on steps, making the sum quicker and more accurate.
2. 5 + 2 + 1 is the same as starting at 5 and counting 3 more.
True False
Two and one together are three, so counting on three after five gives the same total as adding one at a time.
3. To add 3 + 1 + 6, we should start at 1.
True False
The largest number is 6, so we should start there and count on 3 and 1 for fewer steps.