[gerdesj]

One of my maths teachers was able to draw up to something like a three foot circle on the blackboard that looked very, very close to ideal every time. He would always use two arcs to do it and it was uncanny. He would whip out a metre/yard rule to do straight lines because they are much harder to do.

Your limbs etc are all a collection of ball and socket/downright weirdly jointed/hinges with benefits/more weirdness. You then want to use this monstrose agglomeration (did I mention how you move the bloody things?) to draw a circle? Obviously you would decide to run a finger over a simulator of a lump with a ball in it and some on/off switches.

People are weird. Nice website though.

[MonkeyClub]

My middle school maths teacher (awesome guy, also had a mustache - mid 90s) taught us how to draw (large) circles on blackboards easily:

Start from the bottom and go counter-clockwise full circle having your arm fully extended. After the first couple of tries, when you build up confidence through the results, the circles get very good. The trick is not moving slowly, but doing it in one go.

The 3'/two ark circles he would do the same way, but using the elbow as the central/pivot point instead of the shoulder.

[gerdesj]

That's how my teacher did it too. Our arms can be loosely described as multiply pin jointed levers after all.

Then we use a "mouse"!

[renewiltord]

There's a meme where a guy does something like this https://www.youtube.com/watch?v=PNNWc4zUvqc

[Nevermark]

I wonder if standing sideways helps too

[aendruk]

At my university the math department held an annual chalkboard circle drawing competition.

[Nevermark]

I am imagining I somehow have a hidden wire up my sleeve creating the radial tension for a perfect circle

Fishing line attached to a collar around my shoulder could could work

—

On a completely different note, in grade school I figured out you can tie fishing line to a pencil and wait for someone to try picking it up. Then give a little jerk so it moves 10 inches or so

People react wildly differently when they suddenly see behavior their mind cannot process! One math teacher walking around the back of class literally jumped up and a gave out a loud “Ieeeyaaa!” shout.

We can react to something much faster than we can think it through