The development of an instructional model for teaching formal mathematical concepts (probability concepts) to disadvantaged high school students through computer programming and some results from a field test are described in this document. The instructional model takes into account both learner characteristics (cognitive, affective, and instrumental abilities) and subject matter requirements. The learner model is based on C. Frankenstein's theory about characteristic faulty patterns of thought among disadvantaged adolescents, namely, difficulties in abstract thinking, irrational thinking, and computational difficulties. The programming approach, which is concrete and procedural, provides a method of abstraction, generalization, and formalization of probability concepts and helps learners assimilate probabilistic concepts into their existing cognitive schemes. Following discussion of the model, examples of the process of detection, identification, and treatment of faulty patterns of thinking, as displayed in a pilot test of the approach, are presented. (RDN)