I give talks to Gardening societies on Alpine Plants. But I am talking to the nearly converted about a slightly different form of gardening. I still lose the attention of a few of them though so that is when I Do the practical demonstration. The changing of a tube may keep their interest as I presume some will be riding bikes.

But you have to have the ability to talk while doing the changing of the tyre. Nothing worse than 3 minutes of silence in the middle of a talk.