Offers a critical commentary on theory-based evaluation, stressing its utility as a method of program planning and as an adjunct to experiments but rejecting it as an alternative to experiments. Cites seven reasons for doubting that theory-based evaluations can provide the valid conclusions about a program's causal effects that proponents have…

Introduces a chemical model illustrating the aspects of the second law of thermodynamics which explains concepts such as reversibility, path dependence, and extrapolation in terms of electrochemistry and calorimetry. Presents a thought experiment using an ideal galvanic electrochemical cell. (YDS)

Aims to determine the pollution content of the water at two locations on Buffalo Creek, Evington, Virginia, by examining the benthic macro-invertebrates that inhabit the test sites. (Author/YDS)

Describes a simple exercise in percolation theory that can be performed easily and quickly in a laboratory using paper and a hole punch. (Author/MM)

Describes a simple laboratory activity illustrating the chemiosmotic principles of active transport in yeast cells. Demonstrates the energy coupling mechanism of active a-glucoside uptake by Saccaromyces cerevisiae cells with a colorimetric transport assay using very simple equipment. (Contains 22 references.) (Author/YDS)

Describes an experiment on the use of problem-based learning. (Author/YDS)

Explains a physics experiment on the dynamics of impact cratering. Measures the spreading velocity of the impact wave and the acoustic signal. (YDS)

Describes a laboratory experiment on surface tension. (Contains 14 references.) (YDS)

Two experiments are reported in which the ratio of the average times spent in the terminal and initial links ("Tt/Ti") in concurrent chains was varied. In Experiment 1, pigeons responded in a three-component procedure in which terminal-link variable-interval schedules were in constant ratio, but their average duration increased across components…

Previous research has demonstrated infants' capacity to discriminate between situations in which all the objects successively hidden behind a screen are present, or not, after the removal of the screen. Two types of interpretation have been proposed: counting capacity or object memorization capacity. In the usual paradigm, the missing object in…

In recent years, interest has been growing in policy applications of different auction systems. This paper reports a series of experiments that were used to design and implement an auction in a unique policymaking environment. In April 2000, the Georgia legislature passed a law that mandated that the state hold an auction in drought years to pay…

How do groups of 3 people establish common ground in problem-solving interactions differently from groups of 2? Do they do this differently when they are supported by videoconferencing technologies? The laboratory experiment reported here manipulated group size and video mediation for participants carrying out a laboratory map task that allowed…

Information about the control of the activity of the 2-oxoglutarate dehydrogenase complex (OGDHC), a key enzyme in the citric acid cycle, is not well covered in the biochemical education literature, especially as it concerns the allosteric regulation of OGDHC by adenine nucleotide and ortophosphate. From experimental work published during the last…

Good quality scientific teaching depends on the ability of researchers to translate laboratory experiments into high school and undergraduate classes, bridging the advanced and basic science with common knowledge. A fast-growing field in biomedical sciences is oxidative stress, which has been associated to several diseases, including cancer and…

Human salivary [alpha]-amylase is used in this experimental approach to introduce biology high school students to the concept of enzyme activity in a dynamic way. Through a series of five easy, rapid, and inexpensive laboratory experiments students learn what the activity of an enzyme consists of: first in a qualitative then in a semi-quantitative…