Explains the problem of analyzing a phase object, separating the contribution due to thickness variations and that due to refractive index variations. Discusses the design of an interferometer and some applications. Provides diagrams and pictures of holographic images. (YP)

Discusses and suggests some solutions for three problems related to chemistry laboratory management, including disappearance of teaching assistants, check in/out procedures, and slow students. (YP)

Provides a step-by-step guide for a simple experiment to measure the approximate percentage of oxygen found in the air that we breathe. Includes background theory, working drawings, chemicals needed, list of supplies, experimental procedure, data evaluation method, and suggestions for extended study. (Author/JJK)

A mechanical analogy between the microscopic motion of a charged carrier in an ordinary resistor and the macroscopic motion of a ball falling along a slanted board covered with a lattice of nails is introduced. The Drude model is also introduced to include the case of inelastic collisions. Computer simulation of the motion is described. (KR)

The classification scheme for periodontal diseases developed in 1989 is discussed, and technologies, both surgical and nonsurgical, for prevention, control, and regeneration of periodontal tissues are described and compared. Research needs are discussed. (MSE)

A procedure for purifying DNA using either bacteria or rat liver is presented. Directions for doing a qualitative DNA assay using diphenylamine and a quantitative DNA assay using spectroscopy are included. (KR)

A laboratory experiment designed to provide rapid, inexpensive student exposure to pharmacogenetics in drug elimination and patient therapy is described. The test, performed on students, determines expression of a drug metabolism enzyme following ingestion of a probe drug. (Author/MSE)

Describes changes to a traditional study of population in yeast colonies. Changes to the procedures include: (1) only one culture per student team; (2) cultures are inoculated only once; and (3) the same tube is sampled daily. (DDR)

Presents some simple demonstrations that students can construct for themselves in class to learn the difference between diffusion and convection rates. Uses cabbage leaves and gelatin and focuses on diffusion in ungelified media, a quantitative diffusion estimate with hydroxyl ions, and a quantitative diffusion estimate with photons. (DDR)

Explains a taxonomy of basic skills of science practicals that is used in the assessment of secondary science students. Details the assessment scheme which involves the evaluation of students through laboratory practical examinations, observational assessment, and written records of academic sessions. (DDR)

Presents two experiments that demonstrate phase changes. The first experiment explores phase changes of carbon dioxide using powdered dry ice sealed in a piece of clear plastic tubing. The second experiment demonstrates an equilibrium process in which a crystal grows in equilibrium with its saturated solution. (PVD)

Recommends that teachers avoid cookbook-type exercises and predescribed protocols for laboratory work and instead engage students in research that can teach critical thinking, problem solving, and analytical skills. (DDR)

Relays one school science technician's experiences in taking a course designed to improve and standardize technician credentials in the United Kingdom. (WRM)

Lists directions for creating some laboratory equipment that makes it easier for students to assess the rate at which an enzyme is modifying its target (substrate). (WRM)

Details laboratory procedures that enable students to understand the concept of how differences in water potential drive the movement of water within a plant in response to transpiration. Students compare transpiration rates for upper and lower surfaces of leaves. (DDR)