Today’s lesson was all about finding out what water resistance does to boats of different shapes and how buoyancy is different between salt water and fresh water. 
The Upper School children investigated these things by making different shaped tin foil boats to race across a tray of water. They saw how the ones with a more streamlined shape went more quickly across the tray because of less water resistance.
They also tested their boats’ buoyancy (upthrust) by filling them with counters. They found that the boat in salty water stayed afloat with more counters than in fresh water. 
Marcus said there was more mass in the salty water so it kept the boat up better! 

Science-water resistance and buoyancy