These are the slides for a basic physics tutorial that is targeted at GCSE (grade 9 and grade 10) standard. In our last video (https://youtu.be/sDlFMf44zUQ) we learned that the average speed of an object can be calculated by dividing the distance travelled by the time it took to travel that distance: average speed = distance / time Distance-time graphs can also be used to represent journeys, and they're particularly useful because it's easy to compare one journey to another at a glance i.e. without having to do any calculations. If the y-axis represents distance, and time is plotted on the x-axis, the slope or gradient of the graph = distance / time, or speed. In the video we take a look at four different examples on a distance-time graph. There is also an associated worksheet (http://www.slideshare.net/NinetyEast/distance-time-graph-exercises) that you can work through to consolidate your understanding.