In this unit, I learned that matter can expand and contract when heated or cooled. I also learned that heat is created many different ways. I also learned that hot air rises and cool air sinks. My favorite thing in this unit was the popcorn lab because it showed you how many different ways you can make popcorn. We also got to try the popcorn. My least favorite thing was the balloon and water bottle lab. Did you enjoy the food coloring lab?