When students participate in computer-mediated learning, their activities are often recorded for learning analytics and educational data mining purposes. While handling student data has associated privacy concerns and is often subject to legal regulations, there is a limited understanding of how educational data is currently managed in practice. To clarify this question, we conducted a survey of over 100 teachers, examining their experience with storing and analyzing student data. The survey identified the wide variety of platforms used to track and store student activity traces, highlighting the necessity to develop common data exchange standards and enforce data management policies that are consistent across platforms. In addition, the responses also revealed a mismatch between platform affordances regarding data tracking and storage, and teacher awareness of such affordances. This disconnect could be mitigated by reinforcing the transparency policies and usability of educational platforms, as well as by improving teacher data management literacy.