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.
Since The Next Generation Science Standards (NGSS) incorporate engineering, I decided to present our fifth and sixth graders with the challenge to design a parachute using household materials. We first talked about how parachutes were actually used to slow down and land Apollo 11 in the water. We also talked about actual structures of parachutes, including good types of material, how they work, etc. I pulled up images of different types of parachutes and we noted that there were differences in shape, strings attached, and even the amounts of chutes connected to make one. After going over the different designs, I set them free with a piece of paper to draw their design. In order to get their materials, the blue-print drawing had to be labeled with exact measurements and materials. These initial drawings could be changed after production began, but I wanted their original designs to be thoughtful.
Production of these parachutes was a long and loud (ask some of my volunteers :) ) endeavor. There was lots of pretesting and going back to the drawing board. Finally launch day arrived. Although the kids hoped we'd get rooftop access, (right!) I determined that the highest and safest place to launch was the top of the primary slide structure. Volunteers acted as announcers, timers, recorders, accuracy checkers, and runners. Teams were vying for spots in the class-selected award categories of Slowest Decent, Most Accurate, Most Aerodynamic, and Coolest Looking. Winners received bragging rights. When all was said and done, the most complicated designs didn't necessarily work the best. The kids learned how to work with others, compromise on ideas, and see their own creations go from design to |