When the road is wet (there is a water layer on the road surface), the road marks become blurred and drivers are distracted. We discuss the contributing processes and identify which processes are dominant to the occurrence of this phenomenon. Modelling and a simple experiment demonstrate that the dominant processes are: (a) refraction of light by…

Recommends black chalkboards, wet-washed before every lecture and advocates the use of Railroad Crayon chalk because its softness and larger size result in a wide high-intensity line. The resulting contrast improves the visibility of material written on chalkboards. (Source for the chalk is provided.) (JM)

Reports on a portable video color camera that is fully suited for seeing ultraviolet images and offers some expanded viewing possibilities. Discusses the basic technique, specialized viewing, and the instructional value of this system of viewing reflectance patterns of flowers and insects that are invisible to the unaided eye. (CW)