Investigated were the effects of increased time allotments, and of the teacher's preference for a particular time allotment, on fourth grade students' achievement in and attitudes to science. The sample involved 324 students from 16 classrooms. Students were randomly assigned to classes, and teachers to the control (minimum time, averaging 20 minutes per day) and experimental (increased time, averaging 35 minutes per day) conditions. Teacher time preferences were determined from a questionnaire. Students were pre- and posttested on science achievement using the Cooperative Sequential Tests of Educational Progress, Science, Form 4A, and an experimenter developed test on the science content taught. Pre- and posttest measures of attitudes were obtained from interviews using Lowery's Projective Test of Attitudes. During the school year all groups gained in science achievement. Changes in attitudes toward science occurred in both directions. No differences significant at the 0.01 level were found attributable to either time allotment or teacher preference for time allotment. No significant interactions were found between students' reading level or I.Q. and time allotment. [Not available in hardcopy due to marginal legibility of original document.] (EB)