This week we were thinking about what makes a vehicle move.  We decided to test how far a car would travel down a ramp when released and no force applied.  We used rulers, metre sticks and a trundle wheel to measure the distance.  We changed the angle of the ramp and found that the car travelled further and faster when the angle was steeper.  We learned about a 'fair' test.  In a fair test only one thing changes eg angle, but everything else must remain the same ie same car, same surface/ramp, same force.