The present project provided for the development of a detailed quantitative curriculum appropriate for use in Head Start classes, trial of the developed materials with preschool children in Hawaii, and preliminary assessment of the curriculum in comparison with a more spontaneous, informal quantitative classroom experience. Directions for tasks related to number and counting, geometry, dimension, prearithmetic operations, and symbols were prepared and revised throughout the school year 1968-69 and presented to 55 children in three experimental classes daily in 20-minute lessons. The tasks were then compiled into a teacher's manual. The Geometric Design, Arithmetic, and Block Design subtests of the WPPSI; an experimental form of the Head Start Arithmetic Test; and two Piagetian conservation tasks were administered to the experimental subjects and 30 subjects in two comparison classes to measure mathematical knowledge and understanding. The mean scores on the WPPSI subtests for the experimental classes were all above the standardized norms and consistently higher than for the comparison classes. The differences were statistically significant on the Geometric Design and Block Design subtests. The net gain on the Head Start Arithmetic Test were also significantly greater for the experimental group than for the comparison group. (Author)