Types of angle
Acute (<90°), right (90°), obtuse (90-180°), straight (180°), reflex (>180°). Year 4/5.
Year 4 names angle types and identifies them by sight. Year 5 measures with a protractor (±1° expected at SATs). Year 6 calculates missing angles on a straight line and around a point.
Worked examples
Right angle = 90° (corner of a square).
Acute < 90°, obtuse 90-180°, reflex 180-360°.
Angles on a straight line sum to 180°; round a point sum to 360°.
Frequently asked questions
Reading the protractor — inner or outer scale?
The 0° that aligns with one arm of the angle determines which scale. Common error: using the wrong scale and getting 60° instead of 120°.
How precise on the SATs?
±2° is the SATs tolerance for measured angles.