MATHCO is a motivating series of audiovisual and print materials designed to overcome the negative effects of sex bias and stereotyping on the attitudes, interests, and aspirations of girls toward mathematics and mathematics-related careers. The materials teach mathematics skills, demonstrate relationships between mathematics and other subjects, and provide exposure to mathematics-related careers. They are useful for boys as well as girls at the pre- and early-adolescent stage; they are both multiethnic and nonsexist in text and illustrations. Module 3 includes a filmstrip and 16 activities linking mathematical concepts and the social sciences. Surveying, planning a trip, scale drawing, population growth, and the stock market are among the topics considered, with activity worksheets for each. (MNS)