## Sunday, December 16, 2018

### A Dozen Interesting Words in SWI

Last Friday's SWI session built upon our previous lesson regarding Measurement and the six different prefixes for the metric stair.

Curious as to whether the student suggestion of < decapod > was actually a real word (or simply a Disney creation for the movie Moana), I looked it up on etymonline. It was real! I had suspected as much since I know the word < podiatrist > has to do with feet. And, as a student reminded me during our class discussion, there's also the word < cephalopod >.

I loved looking around on etymonline and finding other words that had prefixes which we saw on our metric stair. Not only did I want to share the story of < decapod >, more words came up that were really interesting, like the story behind < decibel >. I also am a big fan of going back to the most ancient Proto-Indo-European roots and then clicking on the PIE root and seeing all of the many words that spring from it. It's like discovering a forest with one massive shared root system but many trunks and many branches.

So, we spent our time looking at the story of a dozen interesting words:

1. decapod

2. decibel

3. December

4. percent

5. decade

6. century

7. *dekm-

8. decimate

9. dime

10. dicker

11. dean

12. dozen

A Proto-Indo-European word was orally spoken only, not written down, so it is given an asterisk beforehand. The PIE word *dekm- meant "ten." It was so interesting to try to figure out how modern words such as < decimate >, < dime >, < dicker >, < dean >, and < dozen > all carry a sense of that ancient "ten" in them. Give it a guess and then check yourself by clicking on the links above!

This conversation also reminded my students of our Montessori math work with the Stamp Game called Decurion Division, which uses the analogy of a Roman unit commander to understand division with a two-digit divisor. Our Stamp Game Activity Set also contains Centurion Division problems with a three-digit divisor. Decurion and Centurion were real Roman military titles!