While on holiday I gave two Zentangle classes in Halifax NS. One was a private class. A week before we left home I put an ad on kijiji for a Zentangle class in Halifax. I figured I'd go ahead if there was enough interest and if those interested would help with a location. I had two responses and one lady offered her apartment! In the end, the other lady couldn't make it but we went ahead anyway.
The second class was through my daughter and son-in-law. They have a lively group of four teenage girls that meets for a couple of hours every week to study one of the books in the Ruhi curriculum. The Ruhi Institute's "main sequence of courses aims ... at achieving three overall objectives: providing insights into spiritual matters, imparting knowledge about the Bahá'í Faith, and helping to develop specific acts of service." (wikipedia)
They decided to give an hour of their time that week to an introduction to Zentangle. We did one tile and five tangles. Although that's half what I do in a usual Introduction class, I've done a couple of one hour classes before and it's sufficient.
As they used to say in newspaper social columns, "A good time was had by all." :-)
You can read my daughter's blog post about the class here. Here's the group and the Zentangle tiles they created: