Through hands-on experiments, students show that air takes up space and has weight, just like solids and liquids, proving that it is a real form of matter.

Key Ideas

• Air passes both tests for matter: it takes up space, which is why an upside-down cup pushed underwater stays dry inside, and it has weight, which is why a full balloon is heavier than an empty one.
• Air shows up in daily life in many ways. When it moves, we call it wind. We pull it into our lungs with every breath and push it back out. It inflates tires, sports balls, and balloons.

Vocabulary

• Mass: The amount of matter something is made of.
• Weight: How hard gravity is pulling on an object's mass.
• Air pressure: The force of air pushing on the surfaces around it.
• Atmosphere: The layer of air surrounding Earth, held in place by gravity.
  
  

Discussion Questions

• We know air has weight, but we do not feel it pressing down on us constantly. Why not?
• How would life on Earth be different if our atmosphere were ten times thicker?
• If air has mass and weight, why is it so much harder to measure the weight of air than the weight of a rock?

Supplies:

• Balance scale, bubbles, straw, cup of water, fan, balloon (2)
  • Alternative to balance scale: stick/dowel balanced on a string OR a hanger 
• Bowl of water big enough for you to stick your hand in: 
• Optional: a cup