Friday Fave for September 29

The Fave is writing these words at 9:29 on 9/29 (or the arguably palindromic 9:29 on 29/9 for those outside the US). That means it’s autumn where the Fave resides, and in autumn one’s thoughts turn to lasers.

That’s right. Lasers.

Like how much easier it would be if you could just zap those fallen leaves with lasers. Or how soon it will be winter and many people will have no choice but to amuse themselves with indoor cats chasing laser pointers.

And what goes great with lasers (besides cats and fallen leaves)? Mirrors. Which leads us to the Fundamental Theorem of Laser Pointers:

Lasers + Mirrors = Angle Play

That equation right there is the premise of this week’s Friday Fave: Laser Challenge.

You set the angle of the laser and the mirrors, then click “Try It!” and see the results of your work.


Negative angles, reflex angles, angles greater than 360°….try them all!

We offer several challenges of increasing complexity, and then we invite you to design your own laser challenge. (You’ll need to show it’s solvable before turning it over to your partner.)

So if your students are studying geometry, trigonometry, or physics, come have them celebrate autumn—the season of lasers—with Laser Challenge!

While our minds are on angles, here are a few more angle-based activities to enjoy with a warm cup of cider (but sorry, no lasers).

Complete the Arch

Sector Area

Polygraph: Angle Relationships