standard_description: Find the greatest common factor of two whole numbers less than or equal to 100 and the least common multiple of two whole numbers less than or equal to 12. Use the distributive property to express a sum of two whole numbers 1–100 with a common factor as a multiple of a sum of two whole numbers with no common factor. For example, express 36 + 8 as 4 (9 + 2).
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for addition and subtraction. These understandings help students develop fluency and will be helpful later in this lesson when students add and subtract to find unknowns in different positions.
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.
\(4 + 6\)
\(6 + 4\)
\(10 - 6\)
\(10 - 4\)
Student Response
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Activity Synthesis
“Who can restate _____’s reasoning in a different way?”
“Did anyone have the same strategy but would explain it differently?”
“How are all the expressions related?”


aligns: no