PBS
Pbs Kids: Science Rocks: Air Lift
Through this experiment, students are challenged to lift a book (and other items) with just air. Requires simple household items, gallon-size, zipper-lock plastic bag, book, pencil, drinking straw, and tape.
Scholastic
Scholastic: Dirtmeister's Science Lab: The Air Is There
An experiment to see how the temperature of an object affects how high it bounces. This site contains web links and notes for the teacher.
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: Air Pressure Demonstrations
Various demonstrations from the Illinois Institute of Technology of air pressure that can be used as an introduction to a chapter or unit on weather or air. Great examples for visual learners.
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: Does Air Really Exist?
Given a teacher demonstration and various learning stations, the students learn that air is a real substance which occupies space, exerts pressure, and has weight.
Education.com
Education.com: An Air Science Experiment
[Free Registration/Login Required] With three simple items (ball of paper, 2 liter pop bottle & hair dryer) you can demonstrate the reality of air pressure. This experiment is user friendly.