Proving the Pythagorean theorem
- When a reason goes round in a circle — 3 tasks
- Three arguments, one true conclusion — 3 tasks
- Building the proof — 3 tasks
- Is this argument allowed to say that? — 3 tasks
- Going Deeper — 3 tasks
- Practice — 22 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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May the Theorem Be Used? The Pythagorean Theorem — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 lettered triangles, each with an equation of squares and no numbers. Students sort them: the Pythagorean theorem gives this equation; a right angle is known but the wrong side stands alone; or nothing says an angle is right, so the theorem may not be used, however right the angle looks.
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Which Side Stands Alone? The Pythagorean Theorem — Answer Maze 10–15 minutes · 4 sheets
8 boxes on one page, each a lettered triangle with no numbers and the same question: what does the Pythagorean theorem give for this triangle? The wrong answers are the two costliest mistakes: putting the wrong side alone, and using the theorem on a triangle that only looks right. The row of box numbers at the foot is the check.
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Does the Theorem Give It? The Pythagorean Theorem — Mystery Picture 25–35 minutes · 5 sheets
25 lettered triangles, each with an equation of squares and no numbers. Does the Pythagorean theorem give this equation? Is a right angle known, and is the side across from it alone? Fill it or leave it white, and a picture appears.