## Monday, July 31, 2023

### Playful Math Blog Carnival #166

This blog carnival has been around for 14 years. Almost every month for 14 years, someone has added a post to this collection. That's quite a long life for an internet phenomenon. (Congratulations, Denise, for keeping this going!) If you'd like to see any of the previous posts in this series, check them out here. For many years, blogs were a big part of my time online. But not so much lately.

When our number (166 now) was in the 20s, 30s, or 40s, I'd make sure to have that many links. Nope, I don't have time to find 166 great links (and you'd get tired just looking through them). But they're out there. I have learned so much from bunny hopping around the web of math bloggers over the years. And even though blogs aren't the popular thing now, most of the old ones are still out there, waiting for you to find them and get excited.

The 166 puzzle: It turns out that 166 is a 'centered triangular number'. If you start with a dot, and then you put a triangle around that, and a bigger one around that, etc, you get up to 166. How many triangles did you use?

I have just run out of envelopes. How should I make myself one? (a puzzle from Fawn Nguyen) What shape of paper will you use?

Online Mathy games

Geometry Puzzles

Find the blue area

This one stumped me (no trig required).

What fraction is shaded? Catriona Shearer (@Cshearer41) made this, along with gobs more, mostly pretty challenging, which she posts on twitter. And here's a collection of over 300 of them.

Beyond the Games & Puzzles

Searching for more? Some good hashtags are:  #MTBoS #ITeachMath  #Elemmathchat #MSmathchat

If you've seen some good math pedagogy out in the wilds of the internet, add a comment.