Presents a procedure for calculating the compass direction and velocity of present plate motions at any geographical point of interest. Includes a table of the relative and geographic motion of the 11 largest plates and a flow chart for determining their present motion. Also offers suggestions for classroom instruction. (ML)

Describes stochastic models. Discusses the rationale for stochastic analysis and modeling, and provides a master equation for the models with respect to chemical processes. Lists 29 references. (YP)

Discusses a single pattern formation mechanism that could underlie the wide variety of animal coat markings found in nature. Presents the results of a mathematical model for how these patterns may be generated in the course of embryonic development. (CW)

Two models are presented. The first assumes that air resistance is proportional to the velocity of the falling body. The second assumes that air resistance is proportional to the square of the velocity. A program written in BASIC that simulates the second model is presented. (MP)

Describes and illustrates the structure of different versions of Mobius bands called prismatic rings or twisted prisms. Different forms are mentioned, such as the one bent into circular shapes and the toroidal polyhedrons. (GA)

A model of Brownian motion is discussed which includes viscosity effects. The model lends itself to Monte Carlo simulation and thus is suitable for an elementary physics laboratory experiment. (BB)

The evolution of ideas about the concept of chaos is surveyed. Discussed are chaos in deterministic, dynamic systems; order in dissipative systems; and thermodynamics and irreversibility. Included are logistic and bifurcation maps to illustrate points made in the discussion. (CW)

Discusses the use of ratio diagrams, which plot the calculations of equilibrium concentrations of the species of the carbonate system. Provides examples to describe how these diagrams can be used to illustrate the behavior systems of interest in volumetric analysis, where absorption or loss of carbon dioxide takes place. (TW)

Discusses the classification of binary oxides as acidic, basic, or amphoteric. Demonstrates how a numerical scale for acidity/basicity of binary oxides can be constructed using thermochemical data for oxoacid salts. Presents the calculations derived from the data that provide the numeric scale values. (TW)

Describes the deterministic simulation (a given input always leads to the same output) and probabilistic simulation (new states are subject to predefined laws of chance). Provides examples of the application of the two simulations with mathematical expressions and PASCAL program. Lists seven references. (YP)

Discusses the use of a computer program designed to solve the mathematical model associated with soil nutrient uptake by plant roots and to predict the nutrient uptake. Describes a user-friendly personal computer version of this program. (TW)

Presents a device to illustrate the concepts of entropy of mixing and the contribution of one term in the Gibb's equation. Notes the device is relatively easy to construct and provides a visual demonstration on diffusion. (MVL)

Presents the origin and mathematics of Hubble's Law of the expanding universe. Discusses limitations to this law and the related concepts of standard candles, elliptical galaxies, and streaming motions, which are conspicuous deviations from the law. The third of three models proposed as explanations for streaming motions is designated: The Great…

When one encounters a problem that one has no adequate way of representing, a new mental model for the problem may have to be found. When a possible model is found, an important next step is to evaluate the validity of the model. In this document, examples of subjects finding and evaluating mental models used as problem representations are…