Ages 12–18
BrainteenAges 13–18MathsWorksheet
Missing angles (Challenge with decimals) · Practice set 1
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Find each missing angle in degrees.
Curriculum links
- Common Core 8.G.A.5: Use informal arguments about angle sums and exterior angles of triangles and angles made by parallel lines and a transversal.
- England NC KS3.MA.GEO.8: Use angles at a point, on a straight line and vertically opposite, and angles with parallel lines.
- England NC KS3.MA.GEO.10: Use the angle sum of a triangle to find the angle sum of any polygon and the angles of regular polygons.
- BNCC EF07MA24: Construct triangles and verify that the interior angles of a triangle add up to 180°.
- BNCC EF07MA27: Calculate interior angles of regular polygons and relate interior and exterior angles.
- Programmes FR C4.MA.EG.1: Use the angle sum of a triangle and angles formed by parallel lines.
Related sheets
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About this activity
What your child practises
Skills: Finding missing angles (level 3).
Applying a method step by step and checking the answer – the skills secondary-school maths tests are built on.
What’s included
- 15 questions
- An answer key you can print with the sheet or on its own
- An on-screen version with instant marking and stars
Age and school year
Made for ages 13–18. That’s Grade 8–12 in the US, Year 9–13 in England, JSS 2 – SS 3 in Nigeria and Class 8–12 in India.
How to use it
- Print it at home or school – it fits a standard A4 or US Letter page.
- Print the answer key too, so marking takes seconds.
- Play it on screen: answers are marked instantly and children earn stars.
- Write on it on a tablet or touchscreen with a finger or stylus – no printer needed.
Tips for parents and teachers
- Redo three of the questions a week later: spaced recall is one of the surest ways to make methods stick.
- Play it on screen for instant feedback, then print a fresh version as a timed, calculator-free check.
- Use a fresh printed copy as a short timed test before an exam to practise working under pressure.
Good to know
- Time needed
- About 20–30 minutes
- You’ll need
- A printer (or a tablet to work on screen), a pencil and an eraser
- Difficulty
- Harder (Challenge with decimals) – pitched at ages 13–18
- Answer key
- Yes – print it with the sheet or on its own