This article seeks to provide researchers and practitioners in laboratory education, particularly those involved in the curriculum design and implementation of teaching laboratories at university level, with a conceptual framework and a working model for an integrated assessment of learning domains, by attending to a more holistic approach to…

A list of demonstrations of discrepant events which have been found to stimulate the curiosity of students in science at the secondary school level are presented. A brief description of the materials and procedures for 15 of these demonstrations is outlined, with short explanations of concepts and principles involved. (MP)

Describes an experiment that provides a study of the different colors and shapes of crystals of transition metal dimethylglyoxime complexes with the use of a low power microscope. Discusses the preparation and examination of the crystals. (CW)

Presents a set of laboratory experiments that can assist students in the detection of carbon dioxide. Offers a variation of the supported drop method of carbon dioxide detection that provides readily visible positive results. Includes background information on carbon dioxide. (ML)

Describes a relatively simple method of extraction and purification of bacterial DNA. This technique permits advanced secondary-level science students to obtain adequate amounts of DNA from very small pellets of bacteria and to observe some of its polymer properties. (ML)

Provides methodology for carrying out the synthesis of sec-butyltoluene by the Friedel-Crafts alkylation of toluene. Suggests using simple elemental aluminum as the catalyst in place of AlCl3 or amalgamated aluminum. Notes satisfactory results for both macro- and microscale operations. (MVL)

Examines the influence of enzyme and substrate concentrations, pH, temperature, and inhibitors on catalytic activity. Follows the influence of different phosphate concentrations in the growth medium on enzyme activity. Studies regulation of enzyme synthesis by repression. Includes methodology for six experiments. (MVL)

Offers several advantages over other possibilities as the enzyme of choice for a student's first exposure to a purification scheme. Uses equipment and materials normally found in biochemistry laboratories. Incorporates several important biochemical techniques including spectrophotometry, chromatography, centrifugation, and electrophoresis. (MVL)

Describes a laboratory experiment to teach the principles of air sampling, gamma ray spectroscopy, nuclear decay, and radioactive equilibrium. Analyzes radon by carbon adsorption and gamma ray counting. Provides methodology and rate of decay equations. (MVL)

Examines the thermal decomposition of sodium bicarbonate to sodium carbonate. Encourages students to predict the end products and to use the stoichiometric results to determine if their predictions are correct. (MVL)

Describes three experiments for undergraduates which illustrate associations of parasites with their host. Includes a table of parasite-induced alterations of selected host species. Instructional suggestions are also provided. (ML)

Describes a laboratory experiment which focuses on the importance of water in germination and seedling emergence. Discusses the activity's design, expected results, and possible application. Offers suggestions for extending the experiment. (ML)

Describes a simple method for purifying catalase for the study of proteins. Procedures are systematically and diagramatically presented. Also identifies polyacrylamide gel electrophoresis, kinetic studies, and apparent molecular weight determination as possible techniques to be used in studying proteins. (ML)

Presents an experiment which enables weed science students to observe first-hand the process of herbicide leaching in soils. Features of this technique which demonstrate the movement of herbicide within a column of soil are outlined. Diagrams are provided of the apparatus employed in the exercise. (ML)