After completing a (very) long unit on parachute design, I decided to spend these next few weeks investigating scientific principles through some hands on explorations. This week, we focused on density. Drawing on what they learned about density early on with an oil, water, and food coloring experiment, we discussed how objects more dense than water sink, and objects less dense float. I then gave them a challenge- Change the shape of a an object (in this case clay) so that it goes from something that sinks to something that floats. Their first task was to roll their piece of clay into a ball and drop it into the water. It sunk like a rock. Then it was up to them to reshape the clay into a design that would float. After much trial and error and comments like, "This is the best experiment ever!", the students started to figure out that by making their clay into the shape of a boat, it would float. Once they figured this out, I challenged them to come up with a shape other than a boat that also floated. Only a few figured this out- an air-filled dumpling-shape. After cleaning up the tables, we discussed why a boat shape or air-filled dumpling would float, but not a fat, thin piece of clay or a clay ball. Density is not about the weight of the object, rather the volume of the object. When we construct a boat, we have sides that hold a pocket of air. This air becomes part of the volume of the clay shape and therefore is less dense than water. We could've also talked about breaking surface tension and water displacement using our clay shapes, but I thought just focusing on density was a big enough topic for one day.