I'm probably much too late, but a 1-hour talk on anything complicated is best used as a "sales" talk to get them interested in learning more. Not that you're selling anything (financially, anyway) but presumably you do want to get them interested enough to either invite you back or do further study on their own (or as a group).

Don't underestimate the difficulty of teaching knots, especially to people who have no prior experience. On the last Wilderness Survival weekend we ran, the other instructor (an ex Naval officer) reduced one of our most reliable and intelligent 16-year old cadets to tears by trying to teach 5 knots in 2 hours. (He wasn't bullying her; she was simply frustrated trying to copy his expert movements. She was struggling to understand the bowline, and he'd already moved on to the sheepshank.) There's a lot more to teaching knots than tying one and expecting everyone to copy you.