Wednesday, September 2, 2009

What's the point?

One of my favorite activities is to have students draw a point on a paper and see how many distinct lines they can draw through the point.  I usually set it up as a competition to see who can get the most lines inside of 15 seconds or so.  On your mark, get set, GO! Pencils start flying.

line through one point

Then to bring the lesson home, I say, "Alright, flip the paper over and put two points on the page.  Now we're gonna see who can get the most lines through both points." 

Ready, set, GO!

They get the first line fast.  Then they panic as they move the ruler and pencil searching for that elusive second line.  Most of 'em end up looking something like this:

confused look

I tease them a bit and we all get a good chuck out of it. I know, I know.  It's not nice to take advantage of these trusting impressionable children.  But I don't care who you are, that thar's funny!


And, they never forget it.


Matt Townsley said...

Outstanding! Who would've known that "two points determine a line." :) Great work and thanks for sharing.

Sarah said...

Because it's been a while since I've said it, I love your writeups of these lessons. And currently no ideas on how to improve this one.

David Cox said...

Ah, I appreciate the encouragement. I try to take what they give me.

The point « Webmaths said...

[...] students just need a quick break before they are ready to refocus. I like David Cox’s “What’s the Point?” [...]

Mathing… » GeoGebra Applet Request – Plane from 3 Points in Space said...

[...] is an effective visual. It should complement well a lesson that is roughly a 3D equivalent of “What’s the Point?” by David Cox from his old wordpress blog. Categories: geogebra, math Tags: 3d, animation, [...]