  Empirical data on early network history are rare. Students beginning their
studies at a university with no or few prior connections to each other offer a
unique opportunity to investigate the formation and early development of social
networks. During a nine week introductory physics course, first year physics
students were asked to identify those with whom they communicated about problem
solving in physics during the preceding week. We use these students' self
reports to produce time dependent student interaction networks. These networks
have also been investigated to elucidate possible effects of gender and
students' final course grade. Changes in the weekly number of links are
investigated to show that while roughly half of all links change from week to
week, students also reestablish a growing number of links as they progress
through their first weeks of study. To investigate how students group, Infomap
is used to establish groups. Further, student group flow is examined using
alluvial diagrams, showing that many students jump between group each week.,
Finally, a segregation measure is developed which shows that students structure
themselves according to gender and laboratory exercise groups and not according
to end-of-course grade. The results show the behavior of an early
social-educational network, and may have implications for theoretical network
models as well as for physics education.
