  Responsive teaching, in which teachers adapt instruction based on close
attention to the substance of students' ideas, is typically characterized along
two dimensions: the level of detail at which teachers attend and respond to
students' ideas, and the stance teachers take toward what they hear -
evaluating for correctness vs. interpreting meaning. We propose that
characterizations of progress in responsive teaching should also consider the
disciplinary centrality of the practices teachers notice and respond to within
student thinking. To illustrate what this kind of progress can look like, we
present a case study of a middle school science teacher who implemented the
"same" lesson on the motion of freely falling objects in two subsequent years.
We argue that his primary shift in responsiveness stemmed from a shift in which
disciplinary practices he preferentially noticed and foregrounded. He moved
from a focus on causal factors or variables to a more scientifically productive
focus on causal stories or explanations. We explore how participation in a
professional development community, institutional constraints, and a shift in
personal epistemology may have contributed to the nature and stability of this
shift in responsiveness.
