Class Opener – Day 3 – The “Circle Guy”

Classes today were presented with a multiple-choice question as they found their seats –

This summer, Mr. L met a math teacher who has won competitions involving:

A) Reciting digits of Pi

B) Multiplying 5-digit numbers quickly

C) Drawing perfect free-hand circles

D) Finding really large prime numbers

Only one of the above choices is correct, and the class voted on which one they believed to be true. The “pi” option received the plurality of votes.  The video below then reveals the correct answer –

And this is how my classes “met” Alex Overwijk, a World Freehand Circle Drawing Champion, and a fine math teacher I had the opportunity to meet at this summer’s Twitter Math Camp.

After some lively discussion over how one apires to be a proficient circle-maker, and why a World Championship even exists for it, some deeper math ideas emerged, in particular…

How would we judge the roundest circle contest?

One student suggested using a compass to make a similar, perfect circle. Piggy-backing, another student thought we could then somehow measure the “white space” between a drawn circle and a perfect circle?

Circles

But what radius should we use? And how do we determine the center of an imperfect circle? So many great questions. To close the opener, I shared how calculus – a few years  down the road – will provide some structure for finding unusual areas.  Always fun to provide some math seeds for experiences down the road.

 

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5 responses to “Class Opener – Day 3 – The “Circle Guy”

  1. great way to set the hook with your students, Bob. Were they eating this up?

  2. There is a website and app for drawing circles….Circle Draw, I believe. The app shows the algorithm used to determine how good the circle is.

  3. I liked this a lot. Interesting discussion in my College Algebra about it.
    Do you think it could connect to Dan’s 3-act: http://threeacts.mrmeyer.com/bestcircle/

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