Paper Airplane
Making paper airplanes and flying them can be hours of fun, and all you need is an 8 1/2 x 11 piece of paper. Fold the piece of paper in half lengthwise. Unfold. Fold down the top 2 corner points down and in along the folded line you first made. Take these two fold flaps and fold them into the center fold line. Repeat by taking the two folds you just created and fold them into the center fold line. Hold onto the center fold and lightly unfold the wings you've been folding in. Now throw it. For more options I took a quick glance online and found the following websites to be very informative on how to make paper airplanes. If you already have a great airplane design, teach your kids and have races. See who's airplane can go the farthest.
http://www.paperairplanes.co.uk/
http://www.josephpalmer.com/ (click on airplanes)
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