Hi, I thought you may like this Mentalrobics exercise from Braingle.com:
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Engineering Challenge : Kite

Engineering challenges are fun activities that are frequently assigned to students in physics or engineering classes, but they can easily be used outside of these venues. An engineering challenge usually has a simple goal and some rules about what sorts of materials you are allowed to use. These are great ways to get people thinking creatively and to foster teamwork and competition. Try an engineering challenge at a birthday party, office outing, scout meeting, or any other gathering where you want to have fun and exercise your creativity.

The objective in the Kite challenge is to construct a kite out of a sheet of paper, plastic drinking straws and tape. The winning kite will be the one to reach the highest altitude with a fixed length of string. If you don't have a windy place nearby, you can allow the contestants to run with the kite to simulate wind. To measure altitude, a simple angle altimeter can be purchased at many hobby stores, or you can create your own with a protractor, string and a small weight.
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For more mind exercises: http://www.braingle.com/mind/