Demonstrate the apparent discrepant effects of sound interference using an easy-to-assemble apparatus. Send a sound wave along two paths of different lengths. What happens if one path is blocked? The result may surprise you and your students! When sound waves interfere with each other, they may reinforce each other and sound much louder. Alternatively, they may also interfere destructively, so the sound becomes very faint or, in some cases, disappears entirely. Build a solid foundation for conceptual understanding by constructing the path length of the apparatus to correspond to the half-wavelength of the 512-Hz tuning fork included with the kit. An effective and fun demonstration as written, it can also be modified to promote inquiry! Challenge students to customize the apparatus for other tuning fork frequencies. Includes student worksheet and comprehensive Teacher Notes with lab hints and teaching tips, sample data, and answers to all questions.