  The Internet provides students with a unique opportunity to connect and
maintain social ties with peers from other schools, irrespective of how far
they are from each other. However, little is known about the real structure of
such online relationships. In this paper, we investigate the structure of
interschool friendship on a popular social networking site. We use data from
36,951 students from 590 schools of a large European city. We find that the
probability of a friendship tie between students from neighboring schools is
high and that it decreases with the distance between schools following the
power law. We also find that students are more likely to be connected if the
educational outcomes of their schools are similar. We show that this fact is
not a consequence of residential segregation. While high- and low-performing
schools are evenly distributed across the city, this is not the case for the
digital space, where schools turn out to be segregated by educational outcomes.
There is no significant correlation between the educational outcomes of a
school and its geographical neighbors; however, there is a strong correlation
between the educational outcomes of a school and its digital neighbors. These
results challenge the common assumption that the Internet is a borderless
space, and may have important implications for the understanding of educational
inequality in the digital age.
