**Which One Doesn't Belong?**Many of us have played with puzzles like that since we were very young. Most of those puzzles had one right answer. Christopher Danielson has been championing versions of this where every item could be the right answer. He's created a 16-page shapes book for young children, built on this principle. And he recently took it out to classrooms around Minneapolis, learning much about kids' understandings of shape.

Christopher's enthusiasm has engendered enthusiasm across the MTBOS (math twitter blog o sphere), and tonight I was able to attend a Big Marker online event discussing a new website dedicated to these puzzles: wodb.ca

What fun!

And so one more nifty tool is added to our techno toolbox for math class. (I have been loving desmos.com for a few years now, and use visualpatterns.org and estimation180.com whenever I get a chance.)