Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
Level 1 · Warm-up
1 Corresponding angles on parallel lines are equal or supplementary?
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Equal.
2 A corresponding angle to 115° is what size? (degrees)
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115°.
3 An alternate angle to 55° is what size? (degrees)
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55°.
Level 2 · Core
4 A co-interior angle to 115° is what size? (degrees)
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180 − 115 = 65°.
5 A co-interior angle to 70° is what size? (degrees)
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110°.
6 Which shape do you look for to spot alternate angles? (a letter)
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A Z shape (or a backwards Z, an N).
Level 3 · Challenge
7 Which of the three parallel-line rules gives angles that are NOT equal?
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Co-interior — they add to 180°.
8 An angle looks clearly bigger than a known 65° angle between the same parallel lines. What is its size? (degrees)
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180 − 65 = 115°.
9 What reason would you write for "x = 55°" when x is in a Z shape with a 55° angle?
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Alternate angles, parallel lines.