standard_description: Determine whether a group of objects (up to 20) has an odd or even number of members, e.g., by pairing objects or counting them by 2s; write an equation to express an even number as a sum of two equal addends.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for making 10 when adding. These understandings help students develop fluency with operations within 20.
When students look for ways to rearrange and decompose numbers to make 10, they notice and make use of structure of expressions and whole numbers (MP7).
Launch
Display one expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: think time
Activity
Record answers and strategies.
Keep expressions and work displayed.
Repeat for each expression.
Student Facing
Find the value of each sum mentally.
\(4 + 8 + 2\)
\(4 + 5 + 3 + 2\)
\(9 + 3 + 1\)
\(9 + 5\)
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Student Response.
Activity Synthesis
“How did making a ten help when finding the sums?”


aligns: no