  Research in student knowledge and learning of science has typically focused
on explaining conceptual change. Recent research, however, documents the great
degree to which student thinking is dynamic and context-sensitive, implicitly
calling for explanations not only of change but also of stability. In other
words: When a pattern of student reasoning is sustained in specific moments and
settings, what mechanisms contribute to sustaining it? We characterize student
understanding and behavior in terms of multiple local coherences in that they
may be variable yet still exhibit local stabilities. We attribute stability in
local conceptual coherences to real-time activities that sustain these
coherences. For example, particular conceptual understandings may be stabilized
by the linguistic features of a worksheet question, or by feedback from the
students' spatial arrangement and orientation. We document a group of
university students who engage in multiple local conceptual coherences while
thinking about motion during a collaborative learning activity. As the students
shift their thinking several times, we describe mechanisms that may contribute
to local stability of their reasoning and behavior.
