standard_description: Partition circles and rectangles into two and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of. Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for making a ten when adding within 20. The numbers chosen lend themselves to making a ten to find the value of the sum. These understandings help students develop fluency and will be helpful later in this lesson when students make a ten when adding one-digit numbers and two-digit numbers.
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 methods.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression mentally.
\(8 + 2\)
\(8 + 5\)
\(9 + 8\)
\(7 + 6\)
Student Response
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Activity Synthesis
“How could
\(8 + 2\)
help you to find the value of
\(8 + 5\)
?” (I can add 2 to 8 to get to 10, and then I have 3 more to add.
\(10 + 3\)
is 13.)


aligns: no