The Combined Modified Design is presented to overcome problems of internal and external validity in the conduct of true experiments in longitudinal studies. It combines a modified version of the Randomized Invitation Design with the lottery longitudinal experimental field trial situation. (SLD)

Details a simple quantitative experiment to measure the percent of oxygen in air. (DKM)

Investigated the development of scientific reasoning in the context of self-directed experimentation. Subjects were fifth and sixth graders and noncollege adults. Found that neither valid strategies nor correct beliefs alone was sufficient to guarantee success, suggesting that regarding experimentation either as domain-general induction or as…

Discusses the impact of various factors on the "charring reaction" of a carbohydrate with concentrated sulfuric acid including the type of sugar, the degree of fineness of the sugar crystals, and the amount of water added. (JRH)

Describes a DNA profile technique that was performed by a group of high school juniors and seniors. (JRH)

Highlights glucosinolates-a family of secondary metabolites from plants of high culinary and nutritional value. Describes experiments that demonstrate the enzymatic degradation of glucosinolates. Teaches students about the distribution, variation, chemistry, and function of a family of natural products important in plant protection, food spicing,…

Describes an apparatus for crystal growth that was designed to study growth kinetics of small crystals from solutions and to obtain crystals of various substances. Describes the use of the apparatus in laboratory practical experiments in the field of crystal growth physics within the course "Solid State Physics". (JRH)

Findings of a review of 64 meta-analytic articles show that experimental data and quasi-experimental or nonexperimental data are sometimes combined incorrectly. Discusses how guidance from proponents of meta-analysis fails to make clear the importance of not synthesizing different kinds of data. (SLD)

Discusses potential sources of self-selection bias in quasi-experimental evaluations of whole-school reform and considers how individual school-level data might be used to provide valid impact estimates. Develops an instrumental variable strategy that can be used to improve on common value-added estimators when only post-treatment measures are…

Presents a laboratory experiment demonstrating the binding of calcium/calmodulin to calmodulin kinase II, which is important in the metabolic and physiological activities of the cell. Uses SDS polyacrylamide gel electrophoresis (PAGE). (YDS)

Presents activities that involve the separation and identification of dyes from mouthwashes and the determination of their alcohol content. Provides a review of various analytical techniques and shows students that more than one instrument or technique may be required to analyze a product. (JRH)

Describes the design and construction of a safe student quantitative conductivity apparatus. Discusses experimental results. (JRH)

Describes an apparatus that is stable and accurate enough for quantitative conductivity experiments but maintains the simplicity of construction and use as well as low cost. Discusses principles and implementation and the performance of the assembled apparatus. (JRH)

Presents an experiment that challenges the claim that sprouting radish seedlings release chemicals into the environment that inhibit germination of lettuce seeds. Reports that although no simple allelopathic demonstration was observed, the experiment provides fertile ground for further experimentation in inquiry-based laboratory experiences. (JRH)

Examines Rousseau's life as continuous experimentation in learning, systematic study, and mechanical arts. Stresses that Rousseau saw that education's wider purpose is to prepare individuals to construct a better society. (SK)