Step 1: Tops
For added longevity, encourage your students to make a top that can out-spin all the others.
Please limit the number of tops your students use to a reasonable number (5 or less).
Wheels can be purchased here.
Step 2: Straw planes and paper aircraft
The Nakamura Lock - A plane that everyone should know
The Acrobat - Very reliable and stable. Can perform loops, or gracefully glide
It is just as important to trim your paper plane as it is to fold it well and choose a good design. Trimming the plane means making adjustments to improve flight performance. For example, if the nose of the plane is diving downward too soon, try bending the tailing edge of the wings upward a little bit. This will produce more lift. If the plane is tilting sideways and crashing, try bending the wings upwards a bit so that the plane has more of a 'V' shape than a 'T' shape when looking at it head-on. This improves stability.
You can take this a step further by adding a paperclip hook to the nose of the plane and then use a slingshot to launch it!