Presents directions for an activity designed to illustrate the function of plant nutrients. (PEB)

The sequence of events preceding the actual discovery of oxygen is reviewed; the circumstances surrounding the discovery and isolation of oxygen by Priestley are examined; and the experiments he carried out are described largely in his own words, taken from his books and papers. (DT)

Describes a chemiluminescence system which can be used to demonstrate the effects of certain factors which affect the rate of reaction (temperature, concentration, catalysis, solvent, etc.), and to perform experiments relevant to the mechanism of the system. (SLH)

Describes a technique which enables the student to observe the relativistic behavior of electrons in a gamma ray detector and compare his results with the classical and relativistic predictions. Shows that it is possible to unambiguously determine the electron's momentum by knowing the Compton edge and photopeak energies of a gamma ray energy…

Second grade children, divided into high and low achievement groups, were tested on a visual vigilance task in which stimuli occurred 24 times in 30 minutes. High achievers responded correctly more often. (ST)

Children's avoidance responses were conditioned and then extinguished in a laboratory analog of a social threat situation. (DP)