lesson
Use the protractor's correct scale
1 · Learn
Angles measure turns in degrees. A right angle is 90°, a straight angle 180° and a full turn 360°. A reflex angle is greater than 180° but less than 360°.
To measure, place the protractor centre on the vertex and its zero line along one arm. Read the scale that starts at that zero. Estimate acute or obtuse first to catch a reversed-scale reading.
2 · Worked example
If an angle clearly looks acute but I read 140°, I check whether the other scale says 40°. I still align the tool carefully before deciding.
3 · Your turn
Classify 35°, 125° and 240° as acute, obtuse or reflex.
Check your answer
35° acute; 125° obtuse; 240° reflex.
4 · Apply your learning
With suitable paper diagrams, measure and draw several angles using a protractor. Ask an adult to check placement, not just the final number.
Adult guidance and safety
Model the calculation or measurement before relying on a procedure. Explain estimates, units and checks. Use a ruler/protractor and suitable diagrams where needed; text examples alone do not establish practical skill or fluency.
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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
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