Reports on the development of a sample course in modern mathematics for elementary teachers. The approach to the course was based on three methodological principles--(1) that emphasis should be placed on mathematics as an organization of (experimental and other) information and not primarily as a deductive system, (2) that it is important to use concrete objects to emphasize the "real " nature of mathematics, and (3) that the material taught in the course should have a direct bearing on the material that the prospective teacher would use in the elementary school classroom. The subject matter of the course consists of a study of the positive real numbers in connection with the measurement process, the study of the whole number line as a one dimensional vector space, and the study of vector geometry in the plane. [Not available in hardcopy due to marginal legibility of original document.] (RP)