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Matter Lab 6-8 / Week 02 / Bench Day
6/6
Week 02 · Solid, Liquid, Gas

Bench Day

Bench Day: State hunt
// The three states of matter and the particles behind them
⏱ about 20 min

Bench Day: State Hunt

Saturday morning, Rocket opens the refrigerator and points. "Solid, solid, liquid, solid, liquid," he says, naming shelves.

"You missed one," Raven says. "The cold air that just rolled out onto your feet."

Rocket laughs. "Gas. The invisible one wins again."

Nova hovers near the freezer door, where a thin white frost coats the edge. "What do you notice here?" she asks, borrowing Raven's question.

"Ice," Rocket says, touching it. "But nobody poured water there. Where did it come from?"

Raven writes the question in the Bench Log with a big circle around it. "Next week," she says. "Today we hunt."

They grab a zip bag and head for the kitchen scale.

  1. Matter normally exists as a solid, a liquid or a gas. A change of state is a physical change; water stays H2O.
  2. A solid keeps its shape and volume. A liquid keeps its volume but takes its container's shape. A gas fills its container.
  3. In a solid, particles are closely spaced and vibrate in place. In a liquid, they stay in contact and slide. In a gas, they are far apart.
  4. Gases are easy to compress because most of a gas is empty space. A liter of air is about 1.2 grams; a liter of water is about 1,000 grams.
  5. Below its melting point a substance is a solid. Mercury is the only metal that is liquid at room temperature.
◇ FAMILY STATE HUNT
Walk through your home together and find ten solids, five liquids and three gases. Write them in the Bench Log.
For each gas, say how you know it is there even though you cannot see it.
Together, seal a zip bag full of air and set it on a kitchen scale. Then seal the same bag full of water and weigh it.
Compare the two masses. Talk about why the same bag holds so much more mass of water than of air.
Find the strangest liquid in the home, such as honey or shampoo. Does it still take the shape of its container?
For a grown-up
The hunt uses only kitchen and bathroom materials that are safe to look at. Nothing is opened, mixed, tasted or smelled up close.
Cleaners and medicines stay on their shelves. A grown-up handles anything hot, sharp or breakable.
This week's facts come from NASA Glenn, the Next Generation Science Standards and LibreTexts, at nasa.gov and libretexts.org.
Safety first
Only water and air go in the zip bags. Seal them fully before weighing.
Never open or sniff cleaners or medicines during the hunt. Point at them and move on.
Wipe up spills right away and wash your hands when the hunt is done.
THINK IT THROUGH
  • Read the question.
  • Tap your answer.
The zip bag of water weighs much more than the same bag of air. Why?
Honey pours slowly but still spreads flat in a bowl. What state is it?
You feel cold air roll out of the refrigerator. How do you know a gas is there?
Which state of matter fills its whole container? Type one word.
WHY THIS EXERCISEEvery gas your family found today was filling the space it was in.
Bench Day checkTrue or false?
A bag of air and the same bag of water have about the same mass.?
Honey is a liquid because it takes the shape of its container.?
You can tell a gas is there by feeling it move.?
A solid changes shape to fit its container.?
WHY THIS EXERCISEThe hunt turns the three state rules into something you can test on anything in your home.
Draw three shelves labeled solids, liquids and gases. Sketch what your family found on each shelf.
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