In this lesson we develop a laboratory experiment in which students quantitatively verify a major theoretical equation for the Doppler Effect when the wave source is at rest with respect to the medium and the observer is moving through the medium. The waves are simulated waves on an iPad or similar device. Ozobot keeps Voyager moving at a known speed, either toward or away from the wave source. Frequencies of the wave when Voyager is at rest, when moving toward the wave source, and when moving away from the wave source are measured from Voyager's light sensor readings. Experimental and theoretical frequencies are compared with differences on the order of only one percent.