I'm now THE committee for physics display case demonstrations and displays at my University, and I'd like your input on what makes an entertaining/pretty, or educational/interesting display case demonstration [preferably change the "or" to an "and", of course].
I do not yet know how many such cases I will be in charge of, nor how large each might be, so space limitations may be a big factor. Nor do I know if any of them will be viewable from all angles. I also don't yet know what kind of power draw limitations each might have (so something that requires a joint recirculating water pump and dehumidifying system might be overkill). On the other hand, I'll have access to each display, so that if something requires periodic maintenance, I can do it.
I suspect that everything from "Here's a lucite-encased meteorite with explanation" display, to interactive chaotic pendulum, to "look at this live barometric feed today and come back tomorrow and compare reading and weather to today's reading and weather", to "drinking bird" might be fine. With some time I could even cobble together a large and imposing and dangerous-looking Jacob's ladder. One which should be easy and probably lots of fun would be to set up a microwave doppler system which could detect people moving around the display and give a nice oscilloscope display of their relative movements.
So: What might draw the eye and the brain? What butterfly wings might plant a seed of wonder in a small visiting child's brain and make him think, years on, that perhaps this science stuff isn't all that boring? What passive or active demonstrations might *you* like to see done well, and what would make them done well for a large range of viewers/users?