Today, we had an exercise in hype and entertainment, and it didn’t even feel like work.
First period, I taught this:
The prescribed curriculum has me teach this way:
- Angles 1 and 2 are supplementary angles, Angle 2 = 40°
- Angles 2 and 10 are alternate interior angles, Angle 10 = 40°
- Angles 8, 9, and 10 make a straight angle, Angle 8 = 60°
- Angles 8 and 11 are alternate interior angles, Angle 11 = 60°
Instead, we did this:
Pass out a ton of triangles, all different shapes. Students cut them out and label the angles. Colored paper helps. Shading the angle helps also for students who have a hard time identifying the vertex.
First, tear off angle A and align its vertex onto the vertex of the straight angle, then the angle side on the side of the straight angle.
Do the same thing with angle B.
Students now have a little gap, as you can see here:
Now, the next part is very important, so I’ll explain it step by step:
1.) Clap your hands loudly and jump on a desk. Sweep your hand over the class and declare, “Magic has arrived!” in a triumphant tone.
2.) You likely have the students’ attention now.
3.) In the same majestic voice, announce, “At this point… every page in the class has a different triangle* with angles labeled differently. All of us have a gap between the two angles.
With my magic powers… I predict… (roll your Rs; it really sets the mood) that your one remaining angle will fit perfectly between the other two… go!”
4.) Students fit the third angle between the first two, then exclaim with wonder and throw roses at your feet. Third period gave a standing ovation and asked how long I was in town. One girl is bringing her parents to the matinee tomorrow.
Spoiler: It’s the Triangle Sum Theorem.
5.) Explain that they can perform the same trick at home, and you’ll give away your secret right now: The sum of all the angles in any triangle is always 180°, just like the straight line upon which they are perched.
See? Wasn’t that better than this?
To be fair, we went actually tackled the above problem after the magic show, but–and you can quote me on this–it’s way easier to hold students’ focus when there is magic involved.
On that note, the book I’ve been promoting for several months finally arrived today from Amazon.
It’s also notable that CUE’s keynote speaker for this year teaches it the other way.
~Matt “Criss Angel” Vaudrey
*There were only 12 different triangles, but I didn’t tell them how to label the angles, so the odds are one in 144 that two students had the same situation.