We put two rulers in the middle of a page with a gap just big enough to fit a marble between them. We sellotaped the rulers to the page in order to stop them from moving. We got one marble and put it between the rulers. We flicked the marble and it moved along the track made by the rulers. We took another marble and put it in the middle of our track. We flicked the first marble and it hit the second marble. When the first marble hit the second marble, it went forward a bit more and then stopped and the second marble kept going. We got the third marble and we put it at the end of the ruler track. We flicked the first marble and it hit the middle marble. The middle marble hit the third marble, which continued off the ruler track. The other marbles stopped on the tracks.
