Floating and Sinking
Students test a variety of objects to see which ﬂoat in water and which sink. They learn that all matter is made of particles, and that the closer together the particles are, the denser the matter. Then they make a sunken egg ﬂoat in water by adding salt to the water and increasing the water's density. From this they conclude that an object will ﬂoat if it is less dense than the liquid that surrounds it.