standard_description: Derive the formula A = 1/2 ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side.
problem_activity: Narrative
The purpose of this What Do You Know About _____? is to invite students to share what they know and how they can represent the number 20.
Launch
Display the number 20.
“What do you know about 20?”
1 minute: quiet think time
Activity
Record responses.
Student Facing
What do you know about 20?
Student Response
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Activity Synthesis
“What connections do you see between different answers?”
Pick two addition expressions that use different addends and ask, “How are these two expressions related?”


aligns: no