During lunch recess, I like to stay inside. Thus, I have been appointed to keep an eye on the gentlemen from the 7th grade who have an extra five or ten minutes to spend inside due to an offense of some sort. One day they were perusing my science and history shelf and brought the Galilean thermometer over to me and asked me what it was.
After I explained how it worked, they asked me if they could make the glass balls inside it move around by warming it up with their hands. I thought that was a neat idea, so I told them to try it. Their time was up before it heated up enough to move the glass balls, so they ran outside.
What a great way to redeem their recess detention time. Maybe we'll try it again another day.