The amount of air in a tire affects its fuel efficiency. Students can learn how air resistance works by working with basketballs. Mark off a 10-meter straightaway on the playground. Remove enough air from the ball so that it will roll with difficulty. Have a student roll the ball down the straightaway and time how long it takes to get to the end or stop. Now add two pumps of air at a time and continue timing how long it takes the ball to roll down the straightaway. Students will see that the ball gets to the far end the fastest, using the same amount of push, when it is properly filled with air.
Air resistance is easily observed in the use of a parachute. This apparatus allows a human being to jump safely from an airplane in flight, because it resists the air and slows the descent. Set up a wooden ramp and help your students attach poster board sails of different sizes to toy cars using dowels. Time the descent of the car down the ramp without a sail, then with sails of different sizes to show students how working against the air slows a vehicle on a slope.
Toy parachutes work on the principal of air resistance, the same as actual parachutes do. Provide each student with string and a plastic grocery bag, so they can make their own parachute to explore air resistance. Have students cut a large square from the plastic bag and cut string into eight pieces of equal length. The strings are tied into eight equally placed holes around the perimeter of the bag. Tie the free ends of the bag around a small object. Students then bunch the bag up and object up and throw it in the air. The resistance will open the parachute and cause the object to float slowly to the ground.
Provide your students with a variety of different types of paper and instruct them to design the best flying airplane possible. Talk to them about air resistance and aerodynamics as they do their designing. For instance, heavier paper needs broader wings to offset more air, according to Archimedes' Principle. Bernoulli's Principle says that curved wings, which have more surface area on top than bottom, will fly better and longer. A pointed nose slices through air resistance, as does a smooth airplane body.