Discusses the principal of formation of shadows, and the speed involved with their appearance or disappearance. (GA)

Describes the design of an experiment that is used to determine the acceleration of an accelerating system with the help of an airtrack and a pendulum. (GA)

Describes the following: a device which converts the displacement of a pendulum into an electric signal and is used as a voltage generator of low frequencies; a turn-by-turn transformer demonstration; how to remove the buoyant force on a piece of cork immersed in water; and how to demonstrate Coulomb's Law on the overhead projector. (GA)

Describes a simple method to measure the size of the Earth to an accuracy of order of magnitude 10 percent. The procedure involves finding the time interval between two sunsets, a sunset observed at sea level while lying down, and a sunset viewed at eye height after standing up. (GA)

An inexpensive DNA preparation is presented which starts with commercially available frozen packed bacterial cells. Methods for analyzing the DNA are also presented, along with physical chemical experiments which can be done using the purified DNA. (BB)

Presents a classroom module designed to utilize Landsat imagery. Includes objectives, materials needed, procedures, and resource information for secondary teachers. (MA)

Describes an experiment for the intermediate undergraduate optics laboratory designed to illustrate simultaneously some aspects of the phenomena of diffraction; interference, coherence, apodization, the Fresnel-Arago law; as well as of the interrelations between these concepts. (HM)

Explains several laboratory exercises using the skin, including the mapping of receptors, counting of sweat glands, computation of total skin area, comparison of various animal skins, measurement of the palm triradius angle, and study of epidermal ridges (dermatoglyphics) in males and females. (CS)

Describes and details the construction of a land-water environment using an aquarium and variety of terrestrial and aquatic materials and organisms. Suggests activities such as identification of organisms, observation of predator-prey interactions, construction of food webs, and recognition of interdependence of biotic and abiotic factors. (CS)

Lists experiments and activities that will aid the young child in understanding the relationship between the position of a body in space and the directions of the force of gravity. (CS)

Describes how to construct a moving reference frame for the quantitative measurement of the Coriolis effect. (MLH)

Suggests and describes laboratory activities in which the Mexican axolotl (Ambystoma mexicanum Shaw) is used, including experiments in embryology and early development, growth and regeneration, neoteny and metamorphosis, genetics and coloration, anatomy and physiology, and behavior. Discusses care and maintenance of animals. (CS)

Describes a simple apparatus that measures atmospheric pressure within 20 percent of the accepted value using a syringe, spring scale, and a ruler. (MLH)

Describes and evaluates introductory physics homework problems done in conjunction with student-performed demonstrations. Discusses them within a process approach to instruction consistent with Piaget's developmental theory. (MLH)

Discusses the preparation of compounds representing six oxidation states of manganese; demonstrations involving these compounds are described. (MLH)