Khan’t Academy?

Hard to believe this video was done as a second attempt after an earlier video was mocked by two math teachers:

http://www.khanacademy.org/math/arithmetic/negative-numbers/v/why-a-negative-times-a-negative-is-a-positive

Part-whole

We’re all familiar with two chronic misconceptions in our math classrooms:

1. Students interpreting the equal sign as an abbreviation for “and the answer is” or “do the things on the left, and then write the answer on the right”;
2. Students failing to recognize fractions as numbers that have all the same characteristics as integers.

This fascinating article describes “part-whole” as a way to address both of these issues. Looks kind of simple, doesn’t it?

LucidChart: Take a difficult concept, and make it better

Can’t wait to assign this to the Algebra 2 kids so they can develop flowcharts to explain how to simplify radical expressions.

Happy New Year

2011=157+163+167+173+179+181+191+193+197+199+211

A sum of 11 consecutive primes. How often does something like that happen?

BTW, 2011 itself is prime.

(Thanks, Audrey!)