A set up of a flat mirror set at 90 deg. to a smooth white surface which contains a sheet of plain white printer paper was prepared.
A strong beam flashlight was prepared with a sheet of construction paper over the lens and a small opening punched in the paper to simulate a narrow beam of light. The beam of light was was shinned on the surface of the paper and parallel to it, and was incident on the mirror at 90 deg. We discussed the reflecting back of the light along the incident beam. This ray of light was termed the normal and defined. It was sketched on the paper as well as a line drawn along the bottom edge of the mirror to represent it. Rays of light were incident on the mirror at other than 90 deg and the light rays sketched. The rays were identified as incident ray, reflected, normal, and the angles formed between normal and incident rays were labeled angles of incidence and reflection. Measuring the angle proved them to be equal and the law of reflection was stated, as the angle of incidence = the angle of reflection.