Describes a theoretical development to explain the shadow patterns of an object exposed to an extended light source while held at varying distances from a screen. The theoretical model is found to be accurate in comparison with experimental results. (MDH)

Describes an experiment used to demonstrate basic physics concepts regarding acoustic waves used by oceanographers to obtain seabed profiles. (ZWH)

Equipped with a plastic film can and a pin, students can gain a better understanding of chromatic aberrations and inner eye phenomena, light, lenses, pinholes, shadows, and ray diagrams. (ZWH)

Uses Dictyostelium discoideum to aid in introducing cell differentiation to students. Students engage in a laboratory exercise that allows them to investigate the means by which embryonic cells choose developmental pathways. (ZWH)

Describes an experiment designed to help students gain a better understanding of the characteristics of various electronic components by incorporating a dual-trace oscilloscope in the X-Y mode in addition to direct observations of phase shifts of various signals into a laboratory exercise. (ZWH)

Presents an inexpensive take-home laboratory activity designed to enhance students understanding of atmospheric pressure by allowing them to engage in a hands-on, discovery approach to physics. (ZWH)

Presents classroom learning activities to help elementary teachers and students learn about and experiment with the sense of taste. One involves tasting an apple while smelling an onion; another involves locating areas of the tongue that respond to salt, sweet, bitter, and sour. (SM)

Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

Presents hands-on science activities that help students learn the concepts of hearing and sound while allowing students to practice science process skills. Students investigate the use of alternative phonograph speakers and needles and apply the knowledge learned to the construction of one-string banjos. (MDH)

Describes the life cycle of the Amaryllis plant from bulb to blossom. Suggests 12 activities in which students monitor plant growth, examine plant parts, make drawings of the plant, and eat flowers of other plants. (MDH)

Describes an inexpensive, reproducible alternative assay that requires minimal preparation and equipment for water testing. It provides students with a direct method of detecting potentially biohazardous material in water by observing the reduction in bacterial luminescence. (PR)

Modifies a laboratory activity to ensure that consistencies exist between the laboratory objectives and the teacher's instructional goals (the constructivist learning theory). The changes are included in the article as well as a rationale for each change. (ZWH)

This article explains how animals are used in research in an effort to counteract animal rights literature. Reveals how medical professionals and others trained in scholarship have misquoted the scientific literature to bolster their claims against the utility of animal research. (PR)

In a hands-on experiment to illustrate the concept of cycles in ecology, students use the Winogradsky column to explore the operation of the sulfur cycle and the interrelatedness of organisms in an environment. Lesson plans include materials needed and class procedures. (MDH)

Antagonism is the production of substances by microorganisms that inhibit or prevent the growth of other bacteria. This paper demonstrates the antagonistic behavior of gram-positive coccus on the B. subtilis and Enterococcus faecalis gram-positive microorganisms, showing that the process of antagonism is sometimes dependent on the nutritional…