Monday, October 28, 2013

The nearsighted man

I heard this problem from a teacher a couple weeks ago -

A nearsighted man can see things only if they’re 3 feet or closer.  If he stands 2 feet in front of a mirror, can he see his reflection?

He said he consistently finds people split on this, and hasn’t found a compelling proof one way or the other.  I humbly offer up the following “proof without words” –  but what does it show?

mirror focus

Wednesday, October 16, 2013

Pancake Toss

I made my kids some Angry Birds pancakes - what better way to serve them than with a high velocity launch?  Use the points to figure out if the second pancake lands on the plate or not!  First one to tell me wins!


Bonus points if you collect some data to find the equation of the first pancake's flight:

Sunday, October 13, 2013

Angry Nerds

Fellow teacher Casey Alexander and I attended the Northwest Math Conference this weekend – I’ll be posting some ideas about it in coming days.  We presented a session called “Angry Birds Teach Math,” in which we shared some Angry Birds math resources, and even shot actual angry birds at the audience. 
angry birds teach math

Tuesday, October 8, 2013

Finding the center of a circle

As I was working on a lazy Susan in my workshop the other day, I needed to find the center of a circle I had made (I had covered up the mark on the other side that I used for the compass).  Luckily I had paid attention in geometry (at least when I taught it), and used a couple of perpendicular chord bisectors.  Thanks, math!
find the center of a circle