In addition to the rock mechanics table, there were things like electrical circuits, optical illusions, ultrasound, gardening, and making silly putty. We all set up our tables in the gymnasium before the kids arrived.
I figured that some of the kids may have already had some introduction to geology, so I brought a small collection of rocks. Sure enough, when I started talking about the rock cycle, a few yelled "Igneous!" and "Sandstone!" (okay, close enough). I also brought the rock with the strain gauges and goniometer, which is always a big hit.
And of course I brought our slider block demonstration of earthquakes. Though once they figured out how the seismometer app worked it was hard to see the small motions of the block sliding over their stomping and banging on the table. I wish I would have taken a picture or two of the kids in action, but once they started arriving I was doing demos almost nonstop for three hours. It was a fun but exhausting day.