ethemes from University of Missouri has pulled together some great resources for teaching Aerodynamics.
Get ready made PowerPoint presentations on flight.
The Smithsonian has lesson plans, links, and activities for teaching about the Wright Brothers
Teach your students how to make a paper airplane.
Check out these resources from kids.gov
Topics include: mythology, history, fundamentals of flight, vehicles, propulsion, structure, controls, animals. There is also a Spanish version
If you don't go anywhere else, check ou The Franklin Institute's Flights of Inspiration It may be all you need or want for developing your lessons!
The Teacher Zone is a good place to begin. Some of the activities you can find there include: Blowing on paper, Make a hot air-balloon, Falling through water, Drag in the bathtub, and More drag ideas.