Today in science we are working on effects of heating and cooling matter.  Today I read them a science story from Yes More Everyday Science Mysteries called Cooling Off.  The story had two brothers doing their science homework at home.  On the homework is asked them what would happen if they had two cups with equal amounts of water and equal temperatures and they poured them together.  One of the boys in the story thought the temperature would be the same and the other brother thought the temperature would double.  We did a 3 corners activity.  They went to one corner if they thought they would stay the same.  They went to another corner if they thought it would double and finally a 3rd corner if they thought it was neither.  Then they had to some up with a way to convince the other group their thinking was correct.  There were split equally between same and double before discussions.  Here was their thinking:
"When you add two of the same temperatures they will stay the same until something hotter or colder gets into them or close to them." Alexa for the group they would stay the same. 
"The same heat and when you take two hot it makes it hotter." Jack for the group that thought they would double.
After discussion they could change groups if their thinking changed.  Most of them moved from the same to double after discussion.  There were only 4 people left in the group who thought it would stay the same.  Then we went and tried it.  They discovered they would stay the same.