I've been scanting the physics content so far with the Tree of SCIENCE!!! posts, so here's one from my own branch of science:
This one is a little Santa/ elf guy with a one-man-band rig, which of course stands for the venerable science of acoustics.
There's lots of great physics material in this one. The tone of the bell that he's carrying will be determined by resonance of sound waves inside the cavity of the bell, and the normal modes of waves on a drumhead is a rich and fascinating topic. The mathematics used to describe these situations is the same basic mathematical apparatus used to describe the propagation of classical light waves, and fairly similar to the basic equations of (non-relativistic) quantum mechanics.
So, let's hear it for acoustics in the Tree of SCIENCE!!!
YAY! Modes and nodes and partials, the three gifts for the baby Jesus. Plus a harmonica.