standard_description: Identify and describe relationships among inscribed angles, radii, and chords. Include the relationship between central, inscribed, and circumscribed angles; inscribed angles on a diameter are right angles; the radius of a circle is perpendicular to the tangent where the radius intersects the circle.
problem_activity: Narrative
The purpose of this estimation exploration is for students to use what they know about fractions to estimate how much of the tape is shaded. Students use what they know about division to determine about how much of the bar is shaded.
Launch
Groups of 2
Display the image.
“What is an estimate that’s too high? Too low? About right?”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Record responses.
Student Facing
The large rectangle represents 1. What fraction of the large rectangle is shaded?
[IMG]
Record an estimate that is:
|                    too low                     |                  about right                   |                    too high                    |
|------------------------------------------------|------------------------------------------------|------------------------------------------------|
| \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\) | \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\) | \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\) |
Student Response
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Advancing Student Thinking
If students do not have an estimate, encourage them to draw on the diagram or cut it out and fold it. Ask students: “How can drawing on or folding the diagram help you figure out how much is shaded?”
Activity Synthesis
“How did you make your about right estimate?” (It looks like there are about 5 of those shaded pieces in the whole rectangle so that’s about
\(\frac{1}{5}\)
.)


aligns: no