Show Atoms in a Box
Review Solid, Liquid, & Gas. Show poster.
Today we are only going to talk about gas. Specifically, we’re going to talk about Air Pressure.
Question: Is air something ?? I don’t believe in air. Prove it to me. You can’t see it, can’t smell it.
Ask the children, to describe how they know that air is real. Hold your breath / cover mouth and nose.
Answer: Blow a hair dryer or a fan. You but you can feel it. Hot air, cool air, moving air.
Question: What is air made of ?? Ans: Atoms & molecules. Show the Box of Atoms.
Notice that atoms bounce off the wall. Do they bounce off your skin ?? Ans: Yes they do.
Air is pushing on your body all the time. We don’t notice it because we are used to it.
Question: What is a Force ? Ans: Pushing or pulling. Have the kids name some examples: Bat a
ball, Tug-o-War, Gravity pulls you down when you fall, etc.
To understand forces, let’s look at an example.
Blow up a Balloon. Why do the walls move to this size ?
Kids push on both sides of a board. (I hold the board, but let it move)
Show diagrams of Forces inside and outside of a balloon.
Question: Is the Force on the balloon all on one spot ? Poke a pencil eraser into the balloon.
Ans: No, the Force is spread out over the surface.
Push with finger tip, push with palm of your hand.(it does make a difference). Which one hurts more ?
Explain Pressure: Poster P = F/A
For older kids only (explain the concept of dividing by Area).
What matters more Force or Pressure ??
Push with finger tip, push with palm of your hand.
Volunteer: Kid steps on 1 cup -> it crushes / Steps on 50 cups -> cannot crush them.
Explain Bed of 1 Nail or 1000 Nails (show a picture) Question: Which one would you rather lay on.
Show the vacuum pump. Kids get to feel the suction at end of the vacuum tube.
Put marshmallow in a Flask (little tiny air bubbles expand)
Show Force diagram / we took away forces on the outside pushing in, so the marshmallow got bigger.
Balloon in the flask -> Balloon gets bigger.
Now what will happen if we take the air pressure away from the inside of something ?
Show that sucking on a straw draws liquid up (reduces pressure / causes a vacuum at one end)
Show the Force diagram / we took away the forces on the inside pushing out.Question: How strong is Air pressure ?
Show crush the can (Boil water in a can, when can is turned upsidedown in tub of water, air instantly
crushes the can) This is a good review of a gas condensing into a liquid, & liquids take up less space.
Question: Are you stronger than Air ?
Sure air pressure is strong enough to crush this thin wimpy little aluminum can, but air pressure cannot
possibly be as strong as you, right ?
Demonstrate the Magdeburg Sphere. 2 kids pull but cannot get it apart.
Conclusion: Air Pressure is stronger than you.
Atoms in a box
Blow dryer or Fan
Diagrams of Forces on a Balloon
Plywood Board (~ 2’ x 2’)
Poster: FORCE, PRESSURE = F/A
Picture of a Bed of 1 Nail / Bed of 1000 Nails
Cup of water or Juice to drink
Vacuum Pump ($150 from FJC)
Vacuum Flask + Stopper
Crush the can (Tub of water, Handle. Cans, Gloves)
Bunsen burner, or propane torch
Fire Extinguisher
Safety glasses
Magdeburg Sphere
Marshmallows
Balloons
Paper cups
Pop cans
Straws
Atoms in a Box
Poster: Solid, Liquid, & Gas
What is air ?
What is a Force
Blow up a Balloon
Poster: Pressure = F/A
Step on cups
Bed of Nails
Marshmallow in a Flask
Crush the Can
Magdeburg Sphere.