Lesson 6 of 10

🧪 Matter: Solid, Liquid, Gas

🎯 Grades 3–5⏱ ~25 min💚 Intermediate

What You'll Learn

  • Identify the three states of matter and their properties
  • Understand how heat energy changes state
  • Name the transitions: melting, freezing, evaporation, condensation

The Three States of Matter

Matter is anything that has mass and takes up space. Almost all matter exists in three states:

  • 🪮 Solid — fixed shape, fixed volume. Particles are tightly packed and vibrate in place. Example: ice, rock, wood.
  • 💧 Liquid — no fixed shape, fixed volume. Particles flow past each other. Example: water, juice, mercury.
  • 🏭 Gas — no fixed shape, no fixed volume. Particles spread out and fill any container. Example: water vapor, air, helium.

Changing States

Adding or removing heat energy causes matter to change state:

  • 🔥 Melting: solid → liquid (add heat)
  • Freezing: liquid → solid (remove heat)
  • Evaporation: liquid → gas (add heat)
  • 💧 Condensation: gas → liquid (remove heat)
  • 🏭 Sublimation: solid → gas directly (example: dry ice)

🧪 Virtual Lab: States of Matter Simulator

Drag the temperature slider to see water change between solid (ice), liquid (water), and gas (steam). Watch the molecules move!

❄ Cold 🔥 Hot 30°C
Quick Check

When liquid water turns to ice, this process is called:

AEvaporation
BFreezing
CCondensation

What is true about gas particles compared to solid particles?

AGas particles are spread far apart and move freely
BGas particles are more tightly packed
CGas particles do not move at all