## Tau Day Limerick

So if working in radians you hate
(How can $\frac {\pi}{4}$ be really $\frac {pie}{8}$?),
Make your life simpler now
By just switching to τ
= 6.28318…

—Denise Gaskins

## Happy Tau Day

6/28 is τ Day.
Tau = τ = one turn around the circle = $\frac{C}{r}$ = 2π = 6.28318…
How do mathematicians celebrate τ Day?
Protest! Share anti-π propaganda.
And eat two pies…

## Math Teachers at Play #39

Welcome to the Math Teachers At Play blog carnival — which is not just for math teachers! If you like to learn new things and play around with ideas, you are sure to find something of interest.

Several of these articles were submitted by the bloggers; others were drawn from my overflowing blog reader. Don’t try to skim everything all at once, but take the time to enjoy browsing. Savor a few posts today, and then come back for another helping tomorrow or next week.

Most of the photos below are from the 2010 MAA Found Math Gallery; click each image for more details. Quotations are from Mike Cook’s Canonical List of Math Jokes.

Let the mathematical fun begin…

## Blog Carnival Broken?

It’s been nearly two weeks since the blog carnival website sent me any articles for the MTaP carnival. If you tried to submit a entry for the carnival this week or last, I probably didn’t get it. Feel free to email me directly!

In the meantime, I’ve combed Google Reader and collected a nice assortment of posts for this week’s Math Teachers at Play — but there is still room for more.

## Drowning Doesn’t Look Like Drowning via Mario Vittone

Off-topic for a math blog, but vitally important:

• Drowning Doesn’t Look Like Drowning

Sometimes the most common indication that someone is drowning is that they don’t look like they’re drowning. They may just look like they are treading water and looking up at the deck. One way to be sure? Ask them, “Are you alright?” If they can answer at all – they probably are. If they return a blank stare, you may have less than 30 seconds to get to them. And parents — children playing in the water make noise. When they get quiet, you get to them and find out why.

• It Doesn’t Have to Be Summer

If something like that seems unlikely to you, then you’d be right. Bucket drownings don’t happen often. But when they do, the parents involved never care how rare the event is for everyone else. Something very similar to the events described above happened just last month in Indiana. There was another bucket drowning reported in Illinois the month before that.

Also worth your time:

## Hyperbolic Crochet Coral Reef

Wow! And to think, I was proud of myself for finishing a crochet afghan. Once.

## Try It Yourself

Chain several. Leave straight to work in rows, or connect into a loop. Single crochet until your patience runs out, increasing every nth stitch (add an extra sc in the same place). Experiment with different colors and patterns. This pdf will give you more ideas.

The more frequently you increase, the frillier your hyperbolic plane will be, while a less-frequent increase makes it easier for students to see the structure. Daina Taimina recommends a 12:13 ratio (increase after every 12th stitch) for classroom use.

Hat tip: 2010 MAA Found Math Gallery, Week 45, and authentic arts by jenny hoople for the pdf.

## Summer Slowdown

It happens this way every summer: I think that when school’s out, I’ll have time to catch up on things. But school is never out, because we’re homeschoolers — and something else always comes up to make us even more busy than normal. This year, an emergency forced dh to move his engineering office from town to home. It’s great to have him close at hand, but spring cleaning has turned into a total house reorganization to make room.

And then Niner and Kitten adopted a couple of new pets. Here’s a picture of Niner’s new snapping turtle. The old one is getting so big he eats feeder fish by the dozen, but she plans to release him back into the creek as soon as the spring floods go down. Kitten rescued two baby birds (normally the dogs take care of wind-blown fledglings), so we have to find room for yet another cage in our menagerie.

In the meantime, this month’s Math Teachers at Play carnival is coming home to my blog, so I’d better get to work on that. If you would like to share a blog post about learning, teaching, or just playing around with math, I’d love to have you send it in. Just click here and fill out the handy automatic submission form.

Update, July 2011: Niner wrote a blog post on the turtles, with photos. Kitten had one of her babies die (sad!) but the other grew up enough to be released into the woods across the creek.