This paper sits within the research on the affordances of new technologies in the mathematics classroom and focuses on a specific feature that is available in dynamic geometry environments, i.e. measuring tools, within the context of conjecturing and proving in open geometry problems. We develop a classification of different modalities of…

Discusses reasons for questioning the underlying assumptions of instruments designed to measure knowledge of the nature of science. Recommends that researchers recognize that conflicting models of science exist, and that each instrument related to these models must specify all philosophic assumptions. (MLH)

The procedure and sampler described permits detection of less than 50pg of one polychlorinated naphthalene (PCN) isomer. The method uses gas chromatography-mass spectrometry. The PCNs are collected on a glass fiber filter and two polyurethane foam plugs and extracted with toluene at 25 degrees Celsius. (BB)

This method of image enchancement and real-time imput of 3-D microscopic objects into an optical pattern recognition system is designed to identify and count diatoms as a means of water pollution assessment. The method consists of directing a low-power laser beam into a microscope to produce a coherent image of the specimen. (Author/BB)

Discussed are two techniques that can be used to directly test the theory that the plates which make up the crust of the earth are still moving. Described are the use of satellite laser ranging and very long baseline interferometry. Samples of data and their analysis are provided. (CW)