Strategy Focus
2 Write a Number Sentence
Lesson
MATH FOCUS: Addition
Learn About It
Read the Problem Kari and her sister Ann went on a 5-mile boat trip. They
rowed for 45 minutes. Then they stopped to have a snack.
After their snack, Kari and Ann rowed another 20 minutes
before stopping for lunch. How many minutes in all did
they row before lunch?
Reread Read the problem carefully.
What question is the problem asking?
●
Which fact will not help you answer the question?
●
Mark
the Text
Search for Information Think about the question in the problem. Circle words and
numbers that will help you answer that question.
Record What facts do you know?
They rowed for
a snack.
minutes until they stopped for
Then they rowed for another
stopping for lunch.
minutes before
© Triumph Learning. OT111eIW2
Think about how you can use these numbers to solve
the problem.
30 Unit 1 Using Place Value, Addition, and Subtraction
Decide What to Do
The question asks how many minutes Kari and Ann rowed
in all. You know the two different numbers of minutes
they rowed.
Ask How can I find how many minutes Kari and Ann rowed
before lunch?
I can use the strategy Write a Number Sentence.
●
I can write an addition sentence.
●
Use Your Ideas
Step 1
You are asked to
find a total.
To write a number sentence, decide whether each
number is an addend or a sum.
The time from the start until the snack is an addend.
The time from the snack until lunch is an
.
The time the sisters rowed in all before lunch is
the sum.
Step 2
Write an addition sentence in words to tell what you
know. Next, write a number sentence. Then find the
missing number.
Minutes rowed
Minutes rowed
+
∙
until snack
after snack
45
+
So Kari and Ann rowed
Review Your Work
20
Minutes in all
before lunch
∙
minutes before lunch.
Look back at the problem. Does your answer make sense?
Why can you use an addition sentence to solve
this problem?
© Triumph Learning. OT111eIW2
Explain
31