Everything is Stuff
Solids, liquids and gases — three dances of the same dots
What this lesson covers
Why it matters
A stone keeps its shape. Water takes the glass's shape. The smell of lunch fills the WHOLE house. Three behaviours, three states — same idea: everything is made of tiny bits.
Predict first
Why does a gas fill the whole room while a stone keeps its shape?
Same H₂O throughout. Heat loosens the grip between molecules: fixed lattice → sliding crowd → free flyers. And all three are MATTER: anything that occupies space and has mass.
- gas particles are free and flying; the stone's are locked in place — correct
- gas is magic
- the stone is too heavy to spread
What you do
Heat the box of particles and watch the dance change: rows → crowd → free flight.
Check yourself
Which has a fixed shape AND a fixed size?
Solids hold both. Liquids keep size, borrow shape. Gases keep neither.
Milk poured from a glass into a bottle changes its…
Liquids reshape to their container — the 200 mL stays 200 mL.
You can smell the kitchen from your room because gas particles…
Free-flying particles wander the whole house — smell is gas on tour.
- a solid — correct
- a liquid
- a gas
- shape but not its amount — correct
- amount
- nothing
- move freely and spread everywhere — correct
- stay in the kitchen
- travel through wires