A parallel line through an external point
- Three windows on one long strip — 3 tasks
- The angle you can control — 3 tasks
- Copy the angle, get the parallel — 3 tasks
- True about the figure, or the reason — 3 tasks
- The parallel without an angle copy — 3 tasks
- Constructing a parallel, and saying why — 24 tasks
- The parallel through a point — 2 tasks
- Build it, and say what makes it parallel — 3 tasks
Classroom activities
Things a class does rather than writes on. Each one is a finished PDF: print it, cut it up if it says so, and hand it round.
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Parallel Through a Point: Which Fact Proves It? — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 finished parallels through a point, every line drawn exactly parallel and every mark left on: sort each by what the marks prove it by — a copied angle, two square corners, or nothing at all, however parallel it looks. The state-exam justification item, on paper.
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Parallel Through a Point: Do the Marks Prove It? — Mystery Picture 25–35 minutes · 4 sheets
25 strangers' finished attempts at the parallel through a point by copying an angle, every arc left on and no numbers: fill the square if the marks prove the line parallel, leave it white if they do not — an angle copied on the wrong side, a reopened compass, a gap never carried, or a line ruled by eye that looks perfect.