This paper is the report of a year-long study of a mathematics teacher's attempts to document her observations of students. One goal of the project is to determine whether it is feasible for a teacher to keep a record of informal assessments such as observations and interviews. Another goal is to determine how useful such information could be to the teacher. Two classes of Algebra I students (N=59) were part of this study which was a collaborative effort involving field notes, videotaping, survey results, audiotaped interviews, teacher notes and records of student progress. Background information is included about the early development of the project, the logistics of documentation methods, and key instructional decisions made by the teacher throughout the project. Important findings of this study highlight the importance of being clear about what is being assessed and the links between that and instruction. The findings also provide a picture of the challenges, from a teachers perspective, of aggregating observation and interview data with other records of student progress. Contains 13 references. (DDR)