From Numberphile: “Sinuosity is a measure of how ‘bendy’ a river is. It is the length of the river divided by the direct route. Featuring Dr. James Grime.”

Update

After posting this video, Dr. Grimes and Lawrence Roberts began collecting and analyzing data about real-world rivers. It turns out the pi theory of sinuosity is too simple. Read about their results:

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From Numberphile: “How accurately can we calculate Pi using hundreds of REAL pies? This video features Matt Parker, who believes this is the world’s most accurate pie-based Pi calculation.”

Pi Day is coming soon. Maybe you’d like to try a pi project with your family? Check out my Pi Day Roundup of links.

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From Numberphile: “Some stuff about Pi, the ‘celebrity number’. This video features maths-loving author Alex Bellos and Professor Roger Bowley from the University of Nottingham.”

Did you notice the error? It was supposed to be “a”…

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Teachers and other math nerds are preparing to celebrate an epic Pi Day on 3/14/15. Unfortunately, the activities I see on teacher blogs and Pinterest don’t include much actual math. They stress the pi/pie wordplay or memorizing the digits.

With a bit of digging, however, I found a couple of projects that let you sink your metaphorical teeth into real mathematical meat. So I put those in the March “Let’s Play Math” newsletter, which went out this morning to everyone who signed up for Tabletop Academy Press math updates.

If you’re not on the mailing list, you can still join in the fun:

In math, symmetry is beautiful, and the most completely symmetric object in the (Euclidean) mathematical plane is the circle. No matter how you turn it, expand it, or shrink it, the circle remains essentially the same. Every circle you can imagine is the exact image of every other circle there is.

This is not true of other shapes. A rectangle may be short or tall. An ellipse may be fat or slim. A triangle may be squat, or stand up right, or lean off at a drunken angle. But circles are all the same, except for magnification. A circle three inches across is a perfect, point-for-point copy of a circle three miles across, or three millimeters…

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Math holiday alert: March 14th is Pi Day. But why limit ourselves to a single day? Playing with math should be a year-round adventure! Here are some ideas to help you celebrate…

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