Angles · Grade 5
In Grade 5 you learn: acute and obtuse angles.
An angle measures an amount of turn. We measure angles in degrees with a protractor and sort them by size: acute, right, obtuse, straight and reflex.
Key facts
- Acute: less than 90°. Right angle: exactly 90°. Obtuse: between 90° and 180°.
- A full turn is 360°.
Worked examples
Example 1
What is the smaller angle between the hands of a clock at 4 o’clock?
Answer: 120°
Example 2
What is the smaller angle between the hands of a clock at 2:30?
Answer: 105°