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.
Other
Federal Aviation Administration: Air Takes Up Room [Pdf]
See how air takes up space by conducting this classroom experiment. With the aid of several common objects, observe the effects of air pressure.
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: The Properties of Air
Lesson plan to teach properties of air. Students use balloons, plastic bottles, plastic bags and a meter stick to conclude that air is a gas that has weight, exerts pressure, and moves.