Build your own avalanche disk to observe granular physics in action. A single granule is a solid but when it interacts with many, it may behave as a solid, liquid, or gas.
I first saw one of these a while back in some science museum that I took Caitlin to. It was more of an art installation where I thought the inside was like one of those lava lamp fluid things. I recently saw a related video to an avalanche disk and it looks like The Museum of Science and Industry - Chicago has one on display. Theirs is 20 ft in diameter and weighs several tons. This one scaled way down. It's one of those things - "How did they do that?" but more importantly, "Can you make it at home?" Other than that, there is a field of science that applies to this.
Learning Objective: Build and use an avalanche disk to observe the behavior of granular solids as granules flow, shear, mix, separate and freeze.
Knowing how granular solids act is pertinent to helping you predict/prevent snow avalanches to designing machines to package your cereal. Computer modelling can be quite complex.
Added Note: This may have been what I really saw, Rheoscopic fluid. Great ible on it too.https://www.instructables.com/id/Making-Rheoscopic...
Video of the Avalanche Disk in action (overdub with your best Carl Sagan impression on the creation of the universe):