Summary
Defines an angle as the opening between two rays and sorts angles into right, acute, and obtuse. Sets up measuring angles with a protractor.
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Teaching resources
Discussion questions
Talk about it
An angle is the amount of turn between two rays that meet at a point. A right angle is a square corner; smaller is acute, wider is obtuse.
- What is a right angle, and where do you see one in the room?
- How is an acute angle different from an obtuse angle?
- What tool do we use to measure how open an angle is?
Quick work-a-long
Vocabulary: angle, ray, right angle, acute.
Try it: Find three right angles in your classroom (corners, books, tiles). Then find one acute angle.