An experiment is described in which the speed of light is measured by time of flight. The equipment in this experiment includes a laser and an acousto–optic modulator. A laser beam was rapidly switched on and off by an acousto–optic modulator and the time that was taken for a light pulse to go a known distance was measured. The group velocity of light was found to an accuracy of about 1.5% using a calibrated oscilloscope as the time reference. Further, by making a least‐squares fit to a set of measurements for different travel times, an uncertainty of 0.5% was obtained. This experiment illustrates acousto–optic modulators, optics, time‐of‐flight instrumentation, and data analysis.