how2GASES Experiments

Progression #1: The "Empty" Glass. Using two tall clear plastic cups or glasses, hold these up to the class and ask them what's inside. The typical answer is, of course, nothing. Then stuff a paper towel inside each one and once again ask what's in it. Ask: What will happen to the paper towel if I put these glasses in a tub of water? Draw attention to how you submerge the glasses.

- Submerge both glasses in the water; one with the open end up; the other open end down.

What happens...The glass you submerged open end up fills with water and the towel gets wet. The water rushes in and displaces the air inside the glass. Examine the second glass that you submerged open end down and the towel. The paper towel did not get wet. Why?

- Re-stuff the dry paper towel inside the dry glass.

- Submerge it again (open side down) then tilt the glass slightly to the side to allow the air to escape. Be sure your class is able to see the air bubble pop up when the glass is tilted.

- Remove the glass from the water and examine the paper towel.

This time the paper got wet. What kept the paper towel from getting wet in the first experiment? What is in the glass that keeps the water out? Air. Present your class with a new clear container (a glass jar). Hold up the "empty" jar and again ask the class, what's inside it? Air. Challenge question: Fill the jar with water, to about half full. Ask, what's inside? Water...and air.



Progression #2: Bubbles & Balls

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