Even large ships weighing hundreds of thousands of tons stay afloat. But how? When a boat floats, it settles into the water, pushing the water aside to make room for itself. But it's a two-way pushing match, the water pushes back on the bottom and sides of the boat. This force, called buoyancy, holds the boat up. In this activity, kids investigate floating by building tinfoil boats and loading them with pennies until they sink. Through testing, kids will discover an important pattern: the boat's size and shape make a difference in how much of a load it can carry. Time to roll up the shirtsleeves and dive in!