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2. Discovery Education Video: A Closer Look at the States of Matter Take a more detailed look at each state of matter and its specific properties.

3. Objects and substances can be changed as they gain or lose thermal energy. Changes in state are one very clear change that can be observed.

4. As a substance continues to gain heat energy, it will transition toward becoming a gas. As the substance becomes warmer, its molecules will move faster and expand, or spread farther apart.

5. As a substance continues to lose heat energy, it will transition toward becoming a solid. As the substance loses thermal energy, its molecules will move slower and contract, or come closer together.

6. Solid LiquidGas MeltingBoiling FreezingCondensation Sublimation Deposition Changes in States of Matter

7. Discovery Education Video: States of Matter: Dry Ice Jeff and Matt demonstrate the explosive power of dry ice. As the frozen carbon dioxide changes from a solid to a gas, the gaseous CO2 expands to fill up its container.

8. Discovery Education Video: Liquid Nitrogen: States of Matter The program presents the properties of nitrogen in both its liquid and gaseous states. As a liquid, nitrogen is able to freeze almost any object. The team films the changes that occur to normally flexible objects after being submerged in liquid nitrogen and dropped onto the laboratory table. Additionally, the team experiments with what happens to liquid nitrogen in a sealed bottle as it warms up to room temperature and becomes a gas.

9. Expansion and contraction of materials must be taken into account during construction projects. Expansion joints allow bridges to expand or contract depending on their temperature.

10. Discovery Education Video: Expansion and Contraction Expansion and contraction occurs when an object is cooled or heated. Designers must take this into account when building bridges and other structures.

11. Discovery Education Video: How Heat Affects Expansion and Contraction of Matter This video clip explains that most matter expands when heated and contracts when cooled. However, water does the opposite, it expands when it freezes to ice, and contracts when warmed. Temperature is measured by thermometers by using either Celsius, or Fahrenheit degrees.

12. Key Questions: 1. Explain what happens to an object or substance as it gains thermal energy. 2. Explain what happens to an object or substance as it loses thermal energy. 3. What would happen to a large bridge that was made out of one single piece of concrete? Explain.