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

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.

In the Paper Boat challenge, participants are asked to make a boat out of paper and a small amount of tape, glue or staples. Everyone should be using the same amount of materials. Each boat will be required to hold a small cargo (marbles, pencils, or little toy figurines work nicely). The boat that remains floating the longest is the winner. A variation of this challenge is to allow teams to use as much or as little paper as they want, but have a heavier cargo (a baseball or book). The lightest boat that can float the cargo for 1 minute is the winner.
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