An experiment was conducted to determine which of three modes of instruction controlling the "density" of simulation training was most effective in terms of transfer and most efficient in terms of the learning rate of preservice teachers. Four goals of the classroom simulation were identified and practiced in three training modes: (1) four at a time, the simultaneous mode; (2) two separately and two together, the combination mode; (3) one at a time, the successive mode. The subjects, undergraduate students in elementary education at Oregon College of Education and University of Oregon in 1965-66 and 1966-67, were randomly assigned to the three treatments, and data was obtained from simulation pre-, post-, and retention tests and from two classroom evaluations of subsequent student teaching behavior. The conclusion after analyses of variance was that the simultaneous method was more efficient. Data revealed no significant interaction of cognitive and personality factors with training modes, but this exploratory phase of the research was limited (as was the total effort) by methodological and conceptual problems. (Included are a 22-item bibliography, standards for teacher behavior, a representative sample of instructor scripts of problem episodes, the simulation training instructions, and descriptions of the measurement instruments and procedures.) (JS)