I can think of two ways to have a class:
First way: We pick a theme (music, art, spanish, etc) and ask members to volunteer teach a single class on this theme (not all members would be expected to volunteer for each theme. Depending on number of volunteers (say, 5), we would teach a class for that many weeks (say, 5 weeks), with each volunteer taking a single week.
Second way: A single member could offer to teach a class on a single theme (say, natural science or crafts) and then teach it weekly, or bi-weekly, or monthly, for a set number of classes.
Do we want to do it one way, the other way, both ways, or something else altogether?