If you’re a parent, you’ve probably heard of Elf on a Shelf. It’s a holiday tradition based on a kid’s book. An elf visits a home during the holidays, sticks around, and reports back to Santa whether children have been naughty or nice. The book has only been around since the 2000s but there’s a lot more to the lore. This week, a Bay Area expert gave a lecture on this history in an unexpected place. KQED’s Azul Dahlstrom-Eckman went and brings us this story.