NASA
Nasa: What Is Lift?
A description of how lift is a mechanical force that requires a fluid moving through a solid object and a change in velocity.
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: Lab Activity: Aviation
This site from the Illinois Institute of Technology provides a student lab activity in which the flight of a paper airplane is investigated and studied. Designed for primary grades, but easily adaptable for junior high students.
Exploratorium
Exploratorium: Science Snacks: Balancing Ball: Suspend a Ball in a Stream of Air
In this lesson plan students learn about air flow using a suspended ball in an air stream.