Every day, but only for parts of the year. (Do I take the average and say "at least once a week?")

It's interactive teaching software (in-class and online) that we've used in the course when it runs, but the course only runs for part of the year.

http://github.com/impressory/impressory

"Supercollaborative" teaching of software engineering is my main project; this was written because I found existing teaching systems didn't support collaborative classes online, and live-interaction in-class, particularly well.