We discussed Archimedes, mentioning his work on levers and weapons as well as his death (supposedly while calculating), but focusing on the story about the crown, the bathtub, and so on. One way to test if the crown was solid gold was to determine if it had the same density as gold. Density is mass/volume -- twice as much mass should take up twice the volume, but dividing them will yield the same value. Mass is related to weight which is easily measured by a scale. Volume could be determined by noting the amount of water displaced when an object is submerged. We went on to discuss the buoyant force -- when an object is placed in a fluid, there is a force equal to the weight of the fluid displaced. (It's only fair since the fluid was previously holding up the fluid that was displaced.) We mentioned pressure (force/area) and floating -- when the object is less dense than the fluid, only enough of its volume is submerged for the buoyant force to balance the weight.)