These background papers are written to provide information for the teacher on technical problems that might arise as students carry on various USMES investigations. Background papers are also written which include information about the types of investigations which may provide good opportunities for learning in specific areas. This set includes papers directly related to: biology, design problems, electric circuits, geometry and shapes, group dynamics, graphical representation, measurement, probability and statistics, ratios, proportion and scaling, and simulation activities. (MK)