Mathematics
Geometry
Procedural
9–10 yrs
Measuring angles (age 9+)
测量角度（9岁以上）
Description
Recognise angle measure as additive; find unknown angles by adding or subtracting on a diagram using equations with a symbol for the unknown
Mastery Evidence
- Two angles on a straight line are 65° and x°; find x = 115°
- An angle is decomposed into 35° and 40°; state the whole angle is 75°
- Solve: angles at a point are 120°, 90°, and x°; find x = 150°
Assessment Prompt
If two angles sit next to each other on a straight line and one is 65°, can your child work out the other angle — knowing that angles on a straight line always add up to 180°?
