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)

Describes a procedure based on the assumption that during the rated lifetime of a light bulb roughly half of the radius of the filament evaporates. Explains how the filament's operating temperature can be deduced. (DDR)

Explores factors that can explain the rapid evolution of the water sciences. Discusses the investment in measuring systems that allow characterizations of water properties and the expansion of mathematical and systemic approaches to the interpretation of data. Contains 23 references. (DDR)

Describes a laboratory employed in undergraduate teaching that uses fruit flies to test student-selected compounds for their ability to cause mutations. Requires no prior experience with fruit flies, incorporates a student design component, and employs both rigorous controls and statistical analyses. (DDR)

A study examined the relationship between the creative thinking of 114 13 to 14-year-old females and scientific problem-solving ability. The students did well in the "preliminary trialing" stage and were more proficient in "interpreting" and "performing" process skills. The other three components, "communication,""planning," and "reflecting,"…