Described is a technique for determining whether a student can conserve matter. This technique utilizes a square-triangle problem. Included are typical answers and Piagetian-type explanations for such answers. (DS)

Reflects on a number of topics relating to science fiction, including the power of good science fiction to spark imaginations and provoke serious thought, the role of women in science fiction, childhood experiences that stimulated the author's thought processes, and the author's experiences as a science fiction writer. (ET)

The author presents parachute play activities that teach not only physical skills and teamwork, but mathematics and science concepts as well. He also gives advice on selecting a parachute. (SJL)

Discusses how the Runge-Lenz vector provides a way to derive the relation between deflection angle and impact parameter for Coulomb- and Kepler-fields in a very simple and a straightforward way. (Author/HM)

Reports an investigation of the effect of gender on ability to recognize simple definitions of concept words in science, as indicated by differences in test scores and in students' free writing "definitions" of physical science concept words. Significant gender differences favoring boys were found for students (n=1,635) of six Tasmanian…

Describes a self-consistent-field-linear combination of atomic orbitals-molecular orbital calculation on the valence electrons of lithium hydride using the method of Roothaan. This description is intended for undergraduate physics students.

Discusses the development of recent analytical techniques that can give detailed information on thin-film structures. (HM)

Discussed is the present concept of the ultimate nature of matter--the elementary particle. An explanation is given for why the lepton family of particles--the electron, muon, and tau--may be truly elementary. The tau lepton is described in more detail. (Author/DS)

This paper draws attention to the frequency meaning of the probability concept and its implications for quantum mechanics. It emphasizes that the very meaning of probability implies the ensemble interpretation of both pure and mixed states. As a result some of the "paradoxical" aspects of quantum mechanics lose their counterintuitive…

A "gedanken photograph" of a relativistic meter stick is analyzed at a level appropriate for undergraduate students. Aspects of the photographic process are analyzed in the frame of the moving meter stick. (Author/SK)

Presents an integral approach to the boundary value problem in waveguides deduced from the Kirchoff's integral formulation of the electromagnetic field. Also, the basis for the numerical solution of more general problems is given, including the example of the isosceles right triangular guide. (Author/SK)

Derives Green's functions and integral equations for scattering solutions subject to a variety of boundary conditions. Exact solutions are obtained for the case of a finite spherical square-well potential, and properties of these solutions are discussed. (Author/HM)

Several standard arguments which attempt to show that the wave function and its derivative must be continuous across jump discontinuities of the potential are reviewed and their defects discussed. (Author/HM)

Deliniates five formulas that are needed to compute a part of several formulas of a reducible representation in spherical symmetry. (SA)

This column generally relates errors which have been discovered in textbooks. The error discussed in this issue is the prevalence of erroneous ideas in organic chemistry textbooks, related to the chemistry of sodium borohydride. (Author/SA)