To celebrate the end of a difficult unit in our grade 8 science program at school I decided to offer my students a design challenge. They had to design a sail boat made only of paper products. They could bring the paper materials from home but if they didn't bring anything, then the only material I supplied was paper. For fasteners I supplied tape, glue sticks, hot glue sticks and staples. Paint was supplied for decoration only and I applied contact cement to each boat for waterproofing. The boat was required to have a sail and to travel 8 feet. It's dimension could not exceed 5" in width and 12" in length. They had 100 minutes to design and race the boat down a river made from an eavestrough. The students competed for the fastest, most attractive and the one that held the most load (loonies). They had a blast. Even the MID kids who find the regular requirements of the curriculum beyond their abilities, delved deep into their designs and many produced boats at home on their own and brought them in for the race.
We had some titanics, some that resembled paper airplanes on water, but overall the designs were great.
When I taught high school technology we were fortunate enough to have a pool in our school. I did a similar project with my grade 10 design & technology students but instead of making a model, they had to make a boat out of cardboard that they could fit into and paddle the length of the pool. Very fun project! Bathing suits required!!