The word "data" connotes math, science, and technology: digits and quantifiable units. Data imply objectification--reducing ideas, and perhaps even students and teachers, to products that can be measured and compared. Ironically, however, this conception of data is itself reductive, and it minimizes the richness and potential of data. Data are much more than numbers and widgets; they involve a wealth of complex and nuanced information. In the field of education, data are collected incessantly. Public attention, naturally, tends to focus on the data that are gathered, analyzed, and used by large organizations, such as state and federal agencies or foundations. Teachers cannot control the way data are used by state and federal political leaders. Teachers can, however, control the way they use data in their classrooms: to support what they believe is important. They can control the reforms that occur in their classrooms and, through these actions, they can seek to influence what occurs in the world. In this era of increasing standardization and assessment-based accountability, teachers may be urged to overlook their own ability to collect, analyze, and report meaningful data about student performance--even though these data can be far more useful and significant than scores on mandated examinations. The author points out that, if teachers are to maintain their professional status and resist the well-documented negative effects of standards-based reform initiatives, they must embrace the data in their classrooms. Classroom data--collected, analyzed, reported, and acted on by teachers--offer the possibility to enhance instructional effectiveness and, ultimately, may be the means to realize truly positive educational reform.