standard_description: Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for adding and subtracting 0 and 1. These understandings help students develop fluency with the count sequence and adding and subtracting within 5.
When students use their knowledge of the count sequence when they add or subtract 1, they look for and make use of structure (MP7).
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 strategy.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression.
\(3 + 0\)
\(3 + 1\)
\(3 - 1\)
\(2 - 0\)
Student Response
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Activity Synthesis
Display
\(3 + 0\)
and
\(2 - 0\)
.
“What is the same about these expressions? What is different about them?” (One is addition and one is subtraction. They both have zero.)


aligns: no