An investigation into friction on the ski slopes. Does waxing skis make them faster? An 8-year-old girl tests three different types of skis - unwaxed, waxed, and self-waxing. She tests each type three times to ensure reliable results. She considers variables and only changes one at a time, making it a fair test.

First broadcast:
5 March 2008

Students could discuss why the waxed and self-waxing skis recorded faster times than the non-waxed skis. They could then design and plan their own friction experiment. A marble race could be set up to explore the friction of different surfaces. Students could set up a ramp using a piece of wooden board propped up under a few books to create a slope, and mark a start and finish line. The ramp could then be covered with different surface materials, such as carpet, sandpaper, vinyl or aluminium foil. Predictions could be made as to which will be quickest. They could then time how long it takes the marble to roll from the start to the finish line and record the results. Students could then analyse results and consider why some surfaces were slower than others. They should be able to conclude that some surfaces created more friction on the marble than others, which slowed down its journey.