more science

On Saturday Cole, dad and I did some science, as usual.   Last Saturday the lesson was on: as temperature rises so does volume of stuff, but the stuff is less dense.  We also made a thermometer/ barometer out of a graduated cylinder with a sealed cap, a straw that goes through the cap, and an oiled piece of cotton inserted in the straw.
How it works:
The hot air inside the barometer has more volume so it pushes the cotton ball up, but when the air is cold  it has less volume causing it to sink.    

our thermometer