This year our science class is studying physics and with every unit there is a project requirement. We just finished learning about weight, mass and density and the properties of floating and sinking. The kids had 3 weeks to design an all metal boat that could carry a load of 50 pennies and float for 10 seconds. We filled up the aquarium and one by one they tested their project. We only had one sinker and I won't tell you who it was. I love science!