Simon Choppin is a Sports Engineer Researcher at the Centre for Sport and Exercise Science at Sheffield Hallam University. He is involved in improving the performance of those involved in sport and exercise, and the equipment and machines that they use. In the first part of this clip he demonstrates a device that measures the reaction time of someone responding to a light appearing in one of 12 positions, by touching it. The number of hits within a 30 second period is recorded. The results can be displayed in two ways, either the response rate in hits per minute, or the average reaction time for one hit. The mathematics involves simple formulae, rounding and decimals. In the second part of this clip he shows how video is used to measure the performance of a new racket. Performance is measured by how far a ball travels in a given time (speed) after impact with the racket. Time is measured in video frames using a camera that records at 1000 frames per second, and distance is measured in ball diameters. The mathematics involves use of simple formulae, measuring in non-standard units and calculations.