More Air Pressure...

Can I lift the newspaper with a yardstick?

Lay a yardstick on a table, with half of the yardstick extending off the table.  Home Depot sells them for 75 cents, but when I told them it was for my class, they donated 10!
cover the ruler with newspaper.  Smooth out and air.

We ask students to make a prediction:  What do they think will happen when we strike the yardstick with our hand in a single whack?  We record their predictions in their notebooks:  Students felt that it would lift and flutter down to the ground (love the descriptive vocabulary). it would be like a kite, the ruler will fly across the room....
We select a student to come up and give it a go.

The newspaper didn't move at all.  The ruler snapped!  

But why?  Well, it is due to the pressure of air on the newspaper.  A yardstick has a small surface area, but the newspaper has a larger area.  At sea level, the air exerts a pressure of about 14 pounds/sq. in.

For a 20inX24in newspaper the surface area is.....?  yep, there's some math in there too!

The weight of air holds a paper down, causing the yardstick to break.

Notebook pages:

 (needs to add the why)

Great links:
http://www.scientificamerican.com/article/bring-science-home-air-pressure-ruler/