ANGLES

Identify acute, right, and obtuse angles, and find missing angles in shapes.

L5L6

CS.GO.4.3·Recognizing and classifying angles(IV)CS.GO.5.1·Measuring and constructing angles(V)

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TYPES OF ANGLES

Angles measure how much two lines turn from each other. Acute angles are less than 90° (sharp). Right angles are exactly 90° (square corner). Obtuse angles are between 90° and 180° (wide). Straight angles are exactly 180° (flat line).

Types of angles

1Acute: less than 90°

2Right: exactly 90°

3Obtuse: between 90° and 180°

4Straight: exactly 180°

LEADER TIP

Use clock hands to show angle sizes. A clock at 3:00 shows a right angle. Protractors come after conceptual understanding.

BEFORE THIS LESSON, TRY

Shapes & Properties

PRACTICE WITH THESE GAMES

Shape Properties

Symmetry Explorer

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ANGLES

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ANGLES