14 March, 2014
Volume 19 No. 11
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In This Issue

The Eratosthenes Experiment

Crazy 8s Math Club

Division and Multiplication of Whole Numbers MOOC-Ed


Online PD

Orientation Sessions

Problem Based Learning Courses

Graduate Credit:
Mathematics Teaching and Learning Certificate

Master's Degree


The Eratosthenes Experiment


How big around is Earth? Step outside and measure it next Friday ... in collaboration with dozens of schools, from the UK to Greece to China, and other latitudes in between!

At their respective noontimes on the equinox, 21 March, students the world over will measure the length of shadows cast by sticks, then consult observations made by others at the same latitude. By sharing these data, invoking the properties of right triangles, and applying proportional reasoning to angular distances, students will obtain a good measurement of our planet's size — a feat first documented by the Greek astronomer Eratosthenes in 240 B.C.

Create a free account with the OpenScienceResources Project to download a lesson plan:


The Eratosthenes Experiment is organized in the framework of the European Commission's Open Discovery Space project. Similar past initiatives, also featured in these pages through the years, have sometimes called this "the Noon Day Measurement."

PoW taking place: math problem-solving moment of the week

"We had SO MANY submissions this week — I enjoyed reading them all, and seeing lots of different strategies. Some were very popular and others, completely unique. The highlighted solutions below represent a wide range of strategies."
- Max, commenting on the Pre-Algebra PoW's Latest Solution

Crazy 8s Math Club


Bedtime Math, whose second book appeared in these pages two weeks ago, announced Tuesday the national launch of an "over-the-top after-school club designed to get kids fired up about math."

Having already piloted with more than a thousand children at 40 schools, libraries, and other accredited after-school enrichment programs, Crazy 8s clubs gather with an adult coach weekly for hands-on "mischief-making" activities such as Bouncy Dice Explosion and Toilet Paper Olympics.

Bedtime Math provides almost all needed materials and instructions. For full details about costs, set-up, and other frequently asked questions, download this FAQ:


Early interest has already outpaced the number of coaches available. Sign up here to join the fun:


Now taking place: math education conversation of the day

"This deserves to be in the editorial section of the NY Times!"
- Dina, posted to the secondary (grades 9-12) discussion group of the Association of Math Teachers of New York State

Division and Multiplication of Whole Numbers MOOC-Ed


How do children move beyond the notion that "multiplication is repeated addition" (MIRA)?

What mathematical distinctions do students make when reasoning with multiple contexts for multiplication and division?

TurnOnCCMath will soon take up these and other questions with its next free, Massive Open Online Course for Educators (MOOC-Ed).

"Division and Multiplication of Whole Numbers: Bridging to Fraction Understanding" will explore how students begin to recognize contextual problems and model with multiplication and division problems, properties, and number facts. Along the way, the MOOC-Ed will identify "where some of the key misconceptions are hiding."

Open to elementary and middle grades educators seeking to understand student multiplicative reasoning, this free MOOC-Ed runs through early May. Even though it begins this coming Monday, 17 March, registration for this self-directed course will stay open through Monday, 31 March:


We last featured TurnOnCCMath in June, upon the launch of its first MOOC-Ed, "The Equipartitioning Learning Trajectory: A K-5 Foundation for Rational Number Reasoning." The team from North Carolina State University offers these courses at no cost as part of research and professional development funding provided by the National Science Foundation (NSF), the William and Flora Hewlett Foundation, the Oak Foundation, the Joseph D. Moore Endowment, and the Friday Institute.


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