Will it work? Gravity and water

This is a very good experiment to show the amazing properties of water and how air pressure works.

Here's what you'll need: Water; a handkerchief; a wine glass; a jar and top; screen; cardboard

Here's what you do: Handkerchief Experiment: Put handkerchief over the wine glass and pour water into the hanky to fill up the glass to about 3/4 full.  Pull the cloth tight over the glass then put your hand over the cloth and turn the glass over gently.  Slowly pull down the sides of the cloth and show how the water stays in the glass.  I've noticed that it works best with a handkerchief. I used 100% cotton.  I tried an old t-shirt but it didn't work well, or at all.
Jar Experiment: Pour water into the mason jar until it's almost full then put the top on with the screen inside.  Put the cardboard over the top, keep your hand over the cardboard and turn the glass over. Pull your hand away and magically the water stays in the glass.  Now pull the cardboard away and even more magically, the water should stay in the glass.   

Why It Works:  Handkerchief Experiment: This shows the amazing properties of water.  The water goes through the cloth when you pour it into the glass and you would expect the water to come out through the same way it went in but when you stretched the cloth tightly around the glass, those holes in the fabric pretty much disappeared and the amazing properties of water took over.  The water molecules were attracted to each other and bonded together to make a thin shield between the openings of the cloth.  It's called surface tension and makes this experiment very cool.

Jar Experiment: The first part of the experiment the water stays in the jar because of air pressure; the pressure of the air outside the glass acting on the pressure the water is placing on the cardboard keeps the water in the glass and prevents it from pouring out. The second part, when the screen is in the jar lid and you pull the cardboard away, the reason lies in surface tension and cohesion (the attraction and joining of the water molecules) that plugs the holes in the screen.  Extremely cool stuff.      

My rating: It gets 4 beakers.  Both of these experiments are real jaw-droppers and they don't require a lot of set-up. 

Once again I have to say that one of the better websites for neat stuff and more information is at the steve spangler website. Check it out.