Side–angle inequalities in one triangle
- The corner you stand in, the fence you see — 3 tasks
- Naming the side opposite an angle — 3 tasks
- Rank the angles, rank the sides — 3 tasks
- When the drawing lies — 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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True, False, or Cannot Tell? Sides and Angles in a Triangle — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 triangles, each with some measures printed and one sentence, such as “AB is the longest side” or “∠C is the largest angle”. Students decide from the numbers alone whether the sentence is true, false, or cannot be told. The pieces mix the two directions, need the third angle found, include two equal angles, and some drawings are drawn against their numbers on purpose. The last row is the limit of the rule: it gives the order of the sides, never a length.
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Which Side Is Across From the Angle? Side-Angle Order — Answer Maze 10–15 minutes · 4 sheets
8 boxes on one page, each a triangle given by its letters and some of its measures: which side is the longest or shortest, which angle is the largest or smallest? The wrong answers are the two costliest mistakes on this topic: naming a side that touches the angle instead of the side across from it, and forgetting to find the third angle when only two are printed. The row of box numbers at the foot is the check.
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Can You Trust the Drawing? Longest Side, Largest Angle — Mystery Picture 25–35 minutes · 4 sheets
25 squares, each a triangle with a question mark on one side or in one angle. With three angles printed: is the marked side the longest? With three sides printed: is the marked angle the largest? Fill the square if yes. Some drawings are drawn against their own numbers on purpose, so only the numbers count, and students who pick a side that touches the largest angle leave a gap in the picture. When every square is right, a picture appears.