Unknown angle problems with parallel lines
- How many different numbers are in the picture — 3 tasks
- Legal, useful, or neither — 3 tasks
- From the given angle to the one you want — 3 tasks
- Drawing the line that is not there — 3 tasks
- Going Deeper — 6 tasks
- Practice — 25 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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Unknown Angles with Parallel Lines — Cut & Glue Sort 25 minutes · 5 sheets
12 figures to cut out and glue into 3 bins — equal, adds to 180°, no way to tell — where the pieces that cannot be told are the ones whose third line carries no arrowheads at all.
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Unknown Angles with Parallel Lines — Answer Maze 15–20 minutes · 4 sheets
One page and nothing to prepare, and every box takes two steps rather than one: find an angle you were not asked for, then use it — and the row of box numbers at the foot shows which box lost a student.
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Unknown Angles with Parallel Lines — Mystery Picture 25–35 minutes · 4 sheets
25 figures and no arithmetic: decide only whether the two marked angles are equal or add to 180°, fill the equal ones with slanted lines, and a picture appears — one square wrong and it has a bite out of it.