I agree with QuiltE about getting lots of practice in before teaching this class. Some people can be very intimidating with all of their questions.
Depending on the knowledge of the class for this technique, you may want to keep it very simple for those who have never tried this method. At the same time you will need to have something just a little more challenging for those who have some experience with it.
Not to complicate things, you may also want to show them the different ways that you can do the stained glass window method. This would give them an overall idea of which technique would be better for them. I took a couple of classes and with one class I was totally frustrated with the way the teacher taught the class. I could not get my blocks covered completely and my bias tape that I was using was too small. The other class I took, the teacher showed different ways to do it and I found I like one method that was really helpful to me.
As for patterns, if you look in some of the stained glass books by Ed Sibbett, Jr., he has some really easy floral designs that would work well with a quilted stained glass design. A lot of his books are published by Dover Books and are very inexpensive and you can find them on Amazon or any bookstore.