Thursday, October 30, 2008

The Perfect Circle

Math teachers always have to draw shapes. We're always graphing lines or parabolas or circles or ellipses, or perhaps drawing solids like spheres or cones or cylinders or prisms.

The Holy Grail for math teachers is to draw the perfect circle. On an overhead projector it's nigh impossible; it's not quite as impossible on a chalk/whiteboard, where you can pivot your arm around the shoulder socket and make a good, large circle, but perfection is difficult. Some teachers can go an entire career without ever achieving this pinnacle of performance.

I have achieved--and on an overhead, too:

Totally freehand. While I was talking. Students tell me I was looking at them, not even looking at the overhead. Totally in the moment.

Bow, my minions!

13 comments:

Anonymous said...

That's an AMAZING circle.

Nice job.

Dan

Mrs. C said...

*clap, clap*

I've seen wooden compass-things for drawing perfect circles on the chalkboard, though, so that might be easier than you think.

MikeAT said...

Right....

Donalbain said...

Holy cow! That is SERIOUSLY impressive.

Another reason though why I love my IWB. Want a perfect circle? Click on the circle tool and voila!

SMiller said...

I know whereof you speak!

On the last regular day of school last year, I went to the whiteboard to demonstrate something about circles, and whipped out the best circle I've ever drawn -- all in one smooth motion, and at 7:45 in the morning! It was such a pretty circle that I also took a picture of it.

Scott McCall said...

i'll bet you didn't want to erase it.

Thorndog said...

Muy impressivo!

gbradley said...

Easy as π

Loni said...

http://www.youtube.com/watch?v=eAhfZUZiwSE

I think yours is better :)

Carson said...

decidedly not egg shaped like my head! impressive

Ellen K said...

When I teach art students to draw circles, I have them repeated lightly draw a scribble with a circular motion. Then I have them look for the perfect circle within the scribble. It works. There's also the method where you draw first the side of the circle away from your dominant hand, and then the other half. Eye hand coordination isn't just for the ball field.

DADvocate said...

Impressive. One of my teachers said that Michelangelo could do this at will.

PeggyU said...

No, that's an ellipse. The foci are .001 mm apart. You can totally tell. ;)