- dip-slip (one tectonic plate slips down)
- strike-slip (the plates slip sideways)
- oblique-slip (one plate slips down and sideways)
All these faults release energy when they move, of course, so we needed to talk about the Richter scale.
I really liked this graphic because it gets across the idea that each number up the scale is 10 times higher than the previous number.
Since the tectonic energy (like all energy) moves in waves, I wanted the kids to see and feel the waves.
We used a large pan of water that we tapped to show the waves. I added a jar in the center to show how the solid core of the earth disrupts the wave pattern- incidentally, that's how they discovered the core was solid, as well as how they measured it's size.
To feel the waves, I had them sit on the floor with their eyes closed while I jumped. I then had them move further and closer so they could feel the effects of distance on the strengths of the waves.
I also set up a seismograph using a shoe box and a weighted pen (those are washers taped to the top of a felt pen). I drew the paper through manually while the kids pounded on the table.
Then we looked at a process known as soil liquefaction. This happens during earthquakes when the water table is high.
We filled a plastic box with dry sand. I put my "building," a glass bottle of water deep into the sand. First they shook the dry sand, and the bottle fell over.
Then we moistened the sand and the bottle was locked in place (no amount of shaking dislodged it). Then we added more water. To the kids' surprise, the bottle fell over with only slight shaking! The waterlogged sand acted as a fluid when it was moved.
We moved outside to look at tsunamis. We used a tub of water and some wooden blocks to look at how the shape of the wave mirrors the shape and movement of the plate underwater.
I had also set up a tsunami model wave pool. It's just an under bed box filled with water and with sand on one side (and sticks representing buildings) and a flat board under the water.
Then it was back inside for the grand finale.
I had made a very large and fairly deep tray of jello. I put a layer of plastic wrap over it and let the kids pat it to make "earthquakes." The thing about jello is that you can actually see the lines of force, the energy waves, as they move through.
I handed out 4 sugar cubes to each kid and they all built "houses" on the jello. They counted down and... I patted the jello vigorously! Earthquake!!!
And then we peeled off the plastic and ate the jello, of course!