This worksheet builds geometric reasoning, teaching students to identify corresponding, alternate and co-interior angles formed when a transversal crosses parallel lines. The worksheet is split into warm-up questions, standard questions and then extension questions to test you.
The concepts it covers:
- A transversal is a line that crosses two (or more) other lines.
- Corresponding angles are in the same position at each intersection — they are equal when the lines are parallel.
- Alternate angles are on opposite sides of the transversal, between the parallel lines — they are equal when the lines are parallel.
- Co-interior (allied) angles are on the same side of the transversal, between the parallel lines — they add to 180° when the lines are parallel.
- Vertically opposite angles (formed by two crossing lines) are always equal, and angles on a straight line always add to 180°.
What your child will practise:
- Identifying which angle relationship applies: corresponding (equal), alternate (equal), or co-interior (sum to 180°).
- Using the equal or supplementary relationship to find an unknown angle from a known one.
- Seting up and solve an equation when angles are given as algebraic expressions.
- Combining angle relationships (e.g. co-interior then vertically opposite) to solve multi-step problems.
- Checking answers make sense: equal-angle pairs should match, and co-interior pairs should sum to exactly 180°.
Every section opens with a worked example, and the download includes a full answer key with step-by-step solutions and teaching notes on the mistakes students most commonly make.
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