Permissions:Copyright (2008) American Association of Physics Teachers. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Association of Physics. The following article appeared in The Physics Teacher, 46(9): 528-531, 2008 and may be found at http://scitation.aip.org/vsearch/servlet/VerityServlet?KEY=ALL&uSeDeFaUlTkEy=TrUe&possible1=Waltner%2C+C.&possible1zone=author&maxdisp=25&smode=strresults&aqs=true