Three things that i learned in this unit are that all matter expands and contracts, water contracts differently than other substances, and that bridges are built with special joints for a special cause. All matter expands and contracts because when the particles gain thermal energy they start to expand. When the particles lose energy the matter contracts. Water contracts differently because it freezes at a certain temperature. While it is losing energy water expands because it forms into rings. Bridges have joint because the pavement needs room to expand and contract. the experiment i liked the most was when we learned about radiation, conduction, and convection using three different ways to make popcorn. My least favorite part of this unit was the test.  I disliked this because Mr. Phillips was absent so we had to write the test instead of doing it on the computer. If you were a particle what item would you be in?