The major purposes of this study were to determine how individual third graders use and understand school time, to ascertain what relationships exist between their use and perception of school time, and to generate conclusions about third graders' use and understanding of school time that would be relevant for educational administrators and teachers in allocating school time as an educational resource. Data for the study were gathered from observations, interviews, and school records of 43 third graders in two ability-grouped units at one of four schools involved in the Resource Utilization Project of the Wisconsin Research and Development Center. The researcher spent 51 days during the 1979-80 school year observing students at the research site. Both qualitative and quantitative methods were used in analyzing the data. Results are discussed in terms of six categories: (1) formal administrative constraints on scheduling of student time; (2) the actual use and control of student time by administration and faculty; (3) actual use and control of time by students themselves; (4) the actual use and control of student time by students and/or administration and faculty; (5) student perception of blocks of school time and control of school time; and (6) the relationship between friendship patterns and school time usage. (Author/RH)