standard_description: Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for adding more than 2 two-digit numbers by making 100. The unit of cents also encourages students to consider how the value could be expressed using dollars, cents, or a combination of the two units. These understandings help students develop fluency.
Launch
Display one expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Activity
Record answers and strategies.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression mentally.
\(80¢ + 20¢ + 37¢\)
\(80¢ + 20¢+ 37¢+ 42¢\)
\(75¢ + 37¢ + 25¢\)
\(75¢ + 80¢ + 25¢ + 20¢\)
Student Response
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Activity Synthesis
Revisit a student strategy that shows looking for a way to make 100 first and expresses the total in cents.
Consider asking:
“Who can restate _____'s reasoning in a different way?”
“Who can restate _____'s reasoning using dollars and cents?”


aligns: no