Friction – a contact force that opposes motion. The sixth grade students at ACS completed an investigation to learn how to reduce the effects of friction when they visited the lab. They discussed the definition, read over the lab, wrote their hypothesis, then, tested their hypothesis. Each group worked together making sure to carry out each step carefully, recording their data as they went along. They measured the force it took to pull a piece of wood along the floor, on a set of marbles, and across sand paper. In the end they were able to observe the effect of friction as a force and have a better understanding of how friction works.