I made these anemometers with my class. They're surprisingly easy and cheap to do. I followed these instructions from the SERCC website.
Here's how I displayed them with a sign saying "Check out our awesome anemometeres!" and details on how to use them. I also stuck up tables for 8 groups to fill in the wind speed on various days [date, rotations in 10 seconds, wind speed (mph), wind speed (kmph)]. Click here to download these signs and record sheets.