My local elementary school already had after schools clubs in place, so I advertised my "programming course", but disguised it in order to make it more attractive to girls.
It was a success. In my first club I had a 4-to-1 ratio of girls to boys.
I had a $5 per kid budget for the club, so I purchased some cheap USB thumbdrives and put Scratch (for both Mac and Windows) and my initial projects on it for the children. However, the school district also installed Scratch on all of the school computers.