As a wrap-up to the Electricity and Electrical Devices unit, students were challenged to build a functional speaker using only four materials. For the actual speaker cone, we had the choice between paper plates and styrofoam plates. Both types were used, so we could hear the difference when connected to the source. I removed the wire from the speakers on my desk and alligator clipped them on the leads from the students’ speakers. Then, we played some music from an iPod connected to a stereo input. They worked much better than I expected – the students were quite impressed with their work as well.