While reading through our text and completing our notes, we read about how seismographs measure the intensity of earthquakes, but there is no better way to explain it than to see one in action.
Last year, I came across a deeply-discounted model of a seismograph in one of the science supply catalogs, so we bought it. The model is a very basic one, just a roll of paper with a stand and a mounted felt-tip pen that moves freely in response to movement.
In class, we used styrofoam blocks cut at an angle to represent tectonic plates meeting at a fault. We sat down around a wobbly table and created some quakes with our "plates." Luckily for us, our classroom table is already pretty wobbly, so it didn't need much help!
We modeled earthquakes at three types of faults - normal faults, reverse faults and strike-slip faults. The seismograph measured the intensity of each.
Below are some images of our "quakes" in action:
Even though our styrofoam blocks made quite a mess of foam dust, it was worth it to see the students really understand how seismographs work and to let them take a break from normal classroom routines and shake things up a little!