standard_description: Understand that a function is a rule that assigns to each input exactly one output. The graph of a function is the set of ordered pairs consisting of an input and the corresponding output. (Function notation is not required in Grade 8.)
problem_activity: Narrative
This warm-up prompts students to carefully analyze and compare attributes of two-dimensional figures with attention to the number of sides, symmetry, and presence of parallel and perpendicular lines. The activity enables the teacher to observe the attributes that students notice intuitively and hear the terminologies they feel comfortable using.
Launch
Groups of 2
Display the image.
“Pick one that doesn’t belong. Be ready to share why it doesn’t belong.”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
2–3 minutes: partner discussion
Share and record responses.
Student Facing
Which one doesn’t belong?
[IMG]
Student Response
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Activity Synthesis
If no students mention parallel sides as an attribute to consider, ask them about it.
Consider asking: “Let’s find at least one reason why each one doesn’t belong.”


aligns: no