Actually I have considered that. To the extent that I was going to encourage my kid to take a cpr/babysitter's class, but then figured, why bother, nobody is going to want to hire a teenaged boy as a babysitter. Which is kind of a shame, really.

But realistically, I don't think people are as suspicious of male volunteers as you might think, otherwise all sports, religion, and boy scouts activities would completely cease. I do think men volunteer in those contexts (and that might also be why they don't volunteer IN school, they're busy doing those things).

I guess I didn't think about it in the school context because there really isn't a chance for you to be alone with the kids, at least not in the events I've volunteered at. Another way you could do that would be a buddy system like "Safe Walk" services (when they had these at my university, two women could walk you home, or a woman and a man, but never two men), where you could pair two parents up together, two moms or one mom and one dad.