Discusses two activities suitable for group involvement or demonstration purposes. The first focuses on factors which determine how much time an object (such as a ball) will take to fall to the ground from a certain height. The second concerns the nonconservation of volume when two soluble liquids are added together. (JN)

A laboratory experiment that involves solving problems with conflicting evidence or inconsistent data. The experiment gives students opportunities to reason as scientists. (EB)

Outlines the discovery and nature of ultraviolet light, discusses some applications for these wavelengths, and describes a number of experiments with ultraviolet radiation suitable for secondary school science classes. (JR)

Briefly discusses the theory of fatigue, and describes ways in which the fatigue rate in humans can be measured in the classroom using a simple physiological instrument, the ergometer. (JR)

Describes how the continuous variation method may be used in senior chemistry classes at the secondary level. This technique allows for the detection of the one or more reactions that may occur in a system over a wide range of composition. (JR)

Describes student activities with mercuric oxide and mercury that help them to form models of the solar system and its creation. (JR)

Presents an outline of current knowledge relating to the response of radicles to a directional source of water (hydrotropism). New techniques are described that may be used in biology classes to demonstrate the hydrotropic response in plants. (JR)

Outlines the advantages of using the readily available eggs of the nematode Rhabditis in studying the early cleavage stages of animal development. Discusses the identification and life history of Rhabditis, how to culture and examine the organism, the cleavage stages and cell lineage, and sources of visual aids. (JR)

Discusses phenomena relating to the nature of soap films and describes soap film experiments suitable for secondary school science students. (JR)