Lesson ​4
States of Matter: Changes with Temperature
Learners observe how many materials, especially water, shift between solid, liquid, and gas states as temperature changes. They finish the lesson by discovering that all states of matter share two key attributes: they take up space and they have weight.

Key Ideas
  • Temperature determines what state a material is in. Most materials can exist as a solid, liquid, or gas depending on how hot or cold they are. We see this most clearly with water.
  • Raising temperature causes melting (solid to liquid). Lowering temperature causes freezing (liquid to solid). Heating further causes evaporation (liquid to gas).
  • All solids, liquids, and gases together are called MATTER. Matter has weight and takes up space. Heat and light do not take up space and have no weight. They belong to a different category entirely: energy.

Vocabulary

  • Melting: The change from solid to liquid caused by raising temperature.
  • Freezing: The change from liquid to solid caused by lowering temperature.
  • Evaporation: The change from liquid to gas caused by raising temperature.
  • Condensation: The change from gas to liquid caused by lowering temperature.
  • Energy: Something that makes things move, change, or happen. Heat and light are forms of energy, not matter.

Discussion Questions
  • If heat causes things to melt, why does the sun not melt rocks on Earth?
  • Water is unusual because it expands when it freezes instead of shrinking like most substances. Why do you think this matters for life on Earth?
  • Is there a temperature at which everything in the universe would be a gas? Is there a temperature at which everything would be a solid?

Digging Deeper Topic
Supplies:
  • Not required, but I recommend demonstrating changes in states of matter with an ice cube and with boiling water.
  • Chart (Solid Liquid Gas Chart) is optional

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L4 Changes in Temperature by Selene

Phet State of Matter Basics Simulation

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