More water Investigations

We did another great experiment that helped us see how water expands when it's heated and contracts when it's cooled.  During this experiment we made "thermometers" out of glass bottles, rubber stoppers, and straws.  First, we took room-temperature water that was dyed green and filled out glass bottles.  Next, we placed the straw inside the rubber stopper and inserted the rubber stopper into the glass bottle.  Water was displaced and was forced up the straw.  We controlled how far the water went up the straw by pushing the stopper in further, or by pulling it out.  It took some careful hands!  We made some guesses about what might have happened when we put the glass bottle into a cup of hot water.  Sure enough, the green water inside the straw began to move up the straw more and more as time went on.  We learned that heating water causes the molecules to move faster and expand.  We wanted to see what would happen when we put the bottle into ice water.  Again, we saw the water inside the straw move, only this time it was moving rapidly down the straw.  That is because when water is cooled the molecules become slower and closer together - also knows as contraction.  It was great fun!