Looking for ideas for a MG-age writing course

I need some advice, and I decided that people who actually get paid to write were the best ones to ask. We homeschool, and although my son likes to write, he's never taken any kind of writing class. Several friends with older kids (middle school) have their kids currently enrolled in a writing class that's good, and that the kids enjoy, but the teacher will be moving on to other projects at the end of the school year and will no longer be able to teach this class. It has been suggested that I teach a writing class. I'm not quite sure I could teach a writing class, for so many reasons. However, if I were to do so, do you have any suggestions? I've only taken one writing class, and I hated it. Before I tried to teach one, I would take another class somewhere (community college probably), but are there any good books out there, or sites, or maybe just ideas of your own?