These materials on geometric probability are the first unit in a course being developed by the Mathematics Department at the North Carolina School of Science and Mathematics. This course is designed to prepare high school students who have completed Algebra 2 for the variety of math courses they will encounter in college. Assuming only a knowledge of linear functions and of areas of simple geometric regions, the unit deals with how to determine probabilities of events for which the number of possible outcomes is infinite. Computer software and a user's guide have been written to accompany the unit. The software provides simulations of seven of the experiments discussed in the unit. These simulations are designed to help students understand the random nature of the experiments and appreciate the relationship between empirical and theoretical probabilities. The unit also provides an introduction to mathematical modeling, computer simulations, and the distinction between discrete and continuous phenomena. (PK)