This dissertation examines the complexity involved in teachers' perceptions and experience of time on school-related activities. The Intensification Theory explains that test-based accountability has caused a time crunch for teachers, increasing their stress level and burnout rate. Research literature has shown that teachers experiencing high levels of stress and burnout correlated with lower student achievement. Teachers, like all professionals, have a finite amount of time, and as the workload increases, less time is left for replenishment and personal family time. Time is a critical resource in schools, and how teachers navigate its use can determine the ultimate success or failure of students. In a variety of ways, researchers have shown an understanding of the relationship between time in school and student achievement. I studied three important aspects of time in a charter school in Florida: (1) How do 3rd grade teachers use their school-related time?; (2) How do 3rd grade teachers and their principals perceive school time?; and (3) How is high stakes accountability perceived to be shaping teacher time? Using observations and interviews, my goal was to give a voice to teachers and administrators regarding how they perceived school time. This was a phenomenological qualitative research study involving five third-grade teachers and two administrators in one K-12 charter school in Florida. It was a high-achieving school with exemplary teachers, who fully experienced the time crunch brought on by test-based accountability. Third-grade was chosen because it was the first grade level at which students experienced repercussions due to achievement scores. With each teacher participant, I conducted semi-structured pre- and post-interviews, completed five full days of observations as a nonparticipant observer, and requested seven full days of time-use diaries for after work hours school-related activities. Two administrators were interviewed to obtain their perspectives on teacher time in order to compare teacher and administrator perceptions. After all data was collected, interviews were transcribed, and subsequently coded using NVivo software. During a preliminary exploratory analysis of the data, I developed themes and patterns relating to teacher time. Details of what occurred in the classrooms during a school week were used to cross-analyze the thematic data and to triangulate time perceptions. After the final analysis of the data, member checking was used to substantiate the accuracy of the findings. Findings related to time as a resource indicated that this third-grade team of teachers spent an average of 54 hours per week working on school-related activities, compared to their contracted workweek of 40 hours. Most often during school hours, teachers were engaged in several activities at once, or rapidly moving from one activity to the next, called context switching. Teachers did most of their instructional planning and professional learning outside paid schoolwork hours. Findings on teacher perceptions of time showed that teachers did not believe that theirs were finite, 9-5 type of jobs, as they spent many hours after contracted work hours completing tasks. Teachers felt they had enough time for instruction if they planned carefully, and left out creative activities. They described the three months before testing as "crunch time", meaning they had to review, re-teach, and squeeze in any standards that were missed, and they shared how stressful this time period was. Administrators perceived that third-grade teachers used time effectively and produced outstanding results, but felt that teachers should have had enough time during paid work hours to complete all their work except grading papers. Responses from administrators on comparing their time with teachers' time were mixed. One administrator thought that teachers had much more control over their own time than did administrators, and one thought exactly the opposite. In the third set of findings, teachers shared their perspectives on the precise pacing required by testing, and how instructional time was lost to time spent using pre-packaged test-preparation materials during crunch time. Administrators noticed that teachers were allowed less leeway for creative activities in their instruction due to the time crunch. I found support in my data for six of the eight assertions of the Intensification Theory, suggesting that teachers' time has become "intensified" due to test-based accountability. My findings regarding the pace of the school day for teachers and interrupted, fragmented time in the classroom confirmed what researchers have learned in the extant literature. Unlike the findings in the research though, Irvin School teachers in my study, were paid for a longer, contracted day than teachers in most schools in the surrounding areas of Florida, and they reported using that extra time to benefit students through greater teacher collaboration, increasing interest in lessons, and reflecting on student mastery of skills. (Abstract shortened by ProQuest.) [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]