In science, we have been testing the density of different objects. If the object you place in the water is more dense then the water, it will sink. If the object you place in the water is less dense then the water, it will float. Two objects that are the same size can have different densities. When we put two pop cans in the water, one Diet Coke and one Mountain Dew, the Diet Coke floated because it is less dense then the water, but the Mountain Dew sunk because it is more dense then the water. Those pop cans are the same size, but they have different densities.