The perpendicular bisector characterization
- Two speakers in a field — 3 tasks
- Two conditions, one at a time — 3 tasks
- From the line to the two distances — 3 tasks
- From the two distances back to the line — 3 tasks
- Going Deeper — 6 tasks
- Practice — 23 tasks
- Summary — 2 tasks
- Cool-down — 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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The Perpendicular Bisector — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 figures to cut out and glue into 3 bins — the marks give you PA = PB, the marks put P on the line, or they give you neither — which is the half of the theorem a class fuses into one and then cannot use.
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The Perpendicular Bisector — Answer Maze 10–15 minutes · 4 sheets
One page and nothing to prepare: every box asks what the figure hands you — the perpendicular bisector, or the two equal lengths — because which half of the theorem applies is the whole difficulty, and the row of box numbers at the foot marks the sheet in a glance.
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The Perpendicular Bisector — Mystery Picture 25–35 minutes · 4 sheets
25 figures and no arithmetic: fill the square with slanted lines where the marks force PA = PB, leave it white where they do not, and a picture appears — a bite out of it is the square to look at again.