Establishes a theoretical basis for both understanding and testing the molecular level assumptions in mixtures. Considers activity coefficient models and equation of state mixing rules. (YP)

The Educational Technology Center (ETC) Complex Systems Project was initiated to explore ways of using computers to help students understand systems which have often proven too complex for most high school students to understand. Preliminary work concentrated on the cognitive processes involved in modeling simple systems. This paper describes an…

Trying to change the predictive rule for the sinking and floating phenomena, students have a great difficulty in understanding density and they are insensitive to empirical counter-examples designed to challenge their own rule. The purpose of this study is to examine the process whereby students from sixth and seventh grades relinquish their…

Describes two computer programs for chemistry: (1) "A Microcomputer Simulation of Fractal Electrodeposition" (provides for the study of fractal aggregrates, BASIC 4.0); and (2) "Counters on Grids" (a game to illustrate the distribution of energy). Notes the programs are available from the authors. (MVL)

The Educational Technology Center (ETC) has devoted the last five years to studying ways of using the computer and other information technologies to teach understanding in science, mathematics, and computing in the nation's elementary and secondary schools. The Center's research has focused on targets of difficulty, topics and concepts that are…