Car Talk Product Placement Puzzler

Great! RAY: There are a lot of our little children who listen to Car Talk who are studying Algebra, so I thought I would ask them to simplify the following polynomial. TOM: Let me just write this down. OK. RAY: X plus A in parentheses times X minus B in parentheses times X plus C […]


Hat tip to Jim Olsen and John Golden: Best spirograph app ever. Thanks for the tip @DrOlsen314! — John Golden (@mathhombre) November 6, 2014 Great activity for kids (and adults) of many levels: How many rotations until the loop is closed?

Car Talk Annulus Puzzler

Awesome! RAY: This puzzler is from a fellow named Jerry Olsen. Ed and his two sons, Biff and Skip, have been hired to paint the floor of a merry-go-round. They want to make sure they measure the floor area exactly, because they don’t want to buy any extra paint. The carousel, of course, is a […]

Skype with Dark Sky

(This is a crosspost from my weekly photo site.) The Introduction to Computer Programming Class had a Skype Q and A with Jason from Dark Sky (Dark Sky is an iOS weather app, check it out, it’s fantastic. They also make the great weather site Super nice guy, I just emailed and asked, and it […]

Kaprekar’s constant

A student talked about Kaprekar’s constant (6174) during their my favorite presentation. Really cool. Steps (from wikipedia): Take any four-digit number, using at least two different digits. (Leading zeros are allowed.) Arrange the digits in descending and then in ascending order to get two four-digit numbers, adding leading zeros if necessary. Subtract the smaller number […]

Euclid GCD

Darker pixel = longer Euclidean algorithm to find GCD(x,y). Here x & y range from 1 to 500. So many questions… — Matt Enlow (@CmonMattTHINK) September 24, 2014 I saw this toot by Matt yesterday morning and I loved the visual of the color based on the number of steps of Euclid’s GCD algorithm. […]

My Favorite for the Students

Let me know if these are things that interest you as a teacher of children: You want the students to find your subject interesting. You want the students to investigate your subject in their own time, like an adult would do. You want the students to continue to develop their presentation skills. You want the […]

Lizard Grow

My son was given this lizard as a big brother gift (can’t find online link to product, but here’s a similar toy). Thoughts? Original Size Size After 2 Day Soak Before Measurements Left image Length: 905 pixels Width (between front feet): 275 pixels 1 inch: 90 pixels Right image Height: 150 pixels 1 inch: 115 […]

M&M’s Mega

"'M&M's Mega' To Have Three Times More Chocolate." Oh brother here we go again. /cc @dandersod — Dan Meyer (@ddmeyer) May 16, 2014 3x the Chocolate? What a great Calculus activity (hint: rotational volumes). Cross sections with an exacto: M&M M&M Mega What shape fits best? Click on image to get directly to the […]

Daily Desmos 3.0

Hello all, we’re looking to reinvigorate the Daily Desmos project and we’re looking for new contributors (and that means you!). We’re taking away the schedule and the numbering system so you can submit posts directly to DD whenever you’d like. You can still submit images via email, but we’re going to increase the number of […]