Interactive surfaces are increasingly common in museums
and other informal learning environments where they are
seen as a medium for promoting social engagement.
However, despite their increasing prevalence, we know
very little about factors that contribute to collaboration and
learning around interactive surfaces. In this paper we
present analyses of visitor engagement around several
multi-touch tabletop science exhibits. Observations of 629
visitors were collected through two widely used techniques:
video study and shadowing. We make four contributions: 1)
we present an algorithm for identifying groups within a
dynamic flow of visitors through an exhibit hall; 2) we
present measures of group-level engagement along with
methods for statistically analyzing these measures; 3) we
assess the effect of observational techniques on visitors’
engagement, demonstrating that consented video studies do
not necessarily reflect visitor behavior in more naturalistic
circumstances; and 4) we present an analysis showing that
groups of two, groups with both children and adults, and
groups that take turns spend longer at the exhibits and
engage more with scientific concepts.