I have a trick for recruiting students for voluntary activities. For example, an enriching day of mathematics, or to contribute writing for community outreach, or to mentor some freshmen. And it's not to make announcements to whole classes to say, come talk to me if you are interested. That doesn't work.
I know people might object to this, because maybe it seems unfair, like opportunities are being limited. (Even though, as I said, the open invitation never works anyway.) But I think of which students would be good candidates. Who has appropriate talents and who will benefit. Then I ask them to take a lap with me around the building (the corridors make a giant rectangle), and I explain what I want them to do, why I think they're the right person to do it, how it will benefit them. And I ask if they would be interested.
It always works. Nobody has ever said no. They usually say something like "I am totally into that." And, they follow through. They jump headlong into these projects with enthusiasm and grace.
It's powerful, the personal invitation. To know your teacher sees something special in you, despite your maybe not being an academic superstar, despite whatever flaws your fears tell you are evident. It's hard to talk back to that.
But, I've been thinking, wow. I need to invite them to learn some math. Frequently. Not as a group - charismatic lecturing is not my forte. Not necessarily every kid every lesson every day. In a way that appeals to their individual talents. Because once it's given a chance, this stuff is startling, beautiful, descriptive. Once they know they bring something to it, and it can benefit them. I have no idea how to pull it off. But I need to find a way.