Grade 5 · Math · Lesson 25

Angles: Types & Measure

An angle is the figure made by two rays that share the same endpoint, called the vertex. The size of an angle is measured in degrees and tells how far one ray has rotated away from the other. Angles show up in shapes, clocks, ramps, and almost every design you see.

What this lesson teaches

1Identify acute, right, obtuse, straight, and reflex angles by their degree range
2Measure an angle in degrees using a protractor
3Classify angles by comparing their measures to 90 and 180 degrees
4Estimate the measure of an angle before measuring to check reasonableness

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