I had a busy day teaching Language Arts yesterday, which triggered my favorite teaching memory.
Several years ago, I was helping out in a middle school science class. The students were doing an experiment in teams, writing their findings in notebooks. Toward the end of the period, there was a mad dash to finish and put their notebooks away. As I watched the pile of notebooks on the bookshelf grow haphazardly tall and come close to toppling completely, I admonished them to “watch the center of gravity.”
At this point, a little sixth-grade girl came up to me and asked, “Doesn’t isostasy mean the same thing?”
I was so surprised I can’t remember my answer. I do remember that, as a half-day job, this was my last class. First I went to the teacher’s lounge where a group was starting lunch and asked “Who is that kid?” Then I went home and looked up isostasy on the Internet.
According to Wikipedia, “Isostasy (Greek ísos “equal”, stásis “standstill”) is the state of gravitational equilibrium between Earth‘s lithosphere and asthenosphere such that the tectonic plates “float” at an elevation that depends on their thickness and density.” (http://en.wikipedia.org/wiki/Isostasy) That doesn’t sound like the same as center of gravity to me, but then I’m not a sixth-grader. Next time, I hope to have a better answer for her.