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 subtracting. The expressions are explicitly chosen to encourage students to use their understanding of the 10 + n structure of teen numbers to subtract (MP7). This method will be discussed in more depth is this lesson's activities.
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 mentally.
\(17 - 7\)
\(17 - 7 - 1\)
\(17 - 8\)
\(17 - 9\)
Student Response
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Activity Synthesis
“Did anyone approach the problem in a different way?”


aligns: no