This is a simple engineering challenge you can do as a patrol challenge.
- a piece of heavy duty tin foil per patrol (make sure they are all the same size)
- some weights such as nickles, washers etc. Just make sure you have a lot of them and they are a consistent weight
- a tub of water.
Each patrol will use their foil to make a boat. The purpose of the boat is to hold up as much weight as possible without sinking. They should be given the opportunity to test their boats out in the water at iterate their design. You might want to make additional pieces of foil available for subsequent designs. At the end, test each patrols best boat with the weights and declare a winner.
Discuss some of the design choices they had to make such as bottom surface area vs height of the sides. You can also see how well the best boats do if you add wind (a hair dryer should do the job) or other conditions.