Hi this is 24m here,About particles and how they rise when hot and go down when cold.Also we found out that water behaves diffrently when it gets cold.And that heat is two particles mixed together and create heat.What i like about this article is.The submarine project cause we had a lot of fun with that expariment.All the times we had to go back and get all the supplies over and over again.And allthe work sheets we had to do in every chapter.What i dont get is how the air in a room circulates around the entire house.