The movie demonstrates the concepts of a point, a line and a ray. We may consider the lighthouse as a point. The light spreads by a line. A ray is the part of a line, which consists of all points lying on one side of a fixed point of the line and the point itself. The fixed point is called the beginning of the ray. Different rays lying on a line and having the common beginning are called supplemental. The beginning of the ray is a projector in the lighthouse. It might be considered as a point.
