Within the already limited literature on instructional practices in detracked classrooms, there are even fewer research‐based studies of detracked science classrooms. This article attempts to address this gap in the research literature, delving into the unique challenges and instructional responses to teaching detracked science. The authors report on a case study of two chemistry teachers' heterogeneous classrooms at a racially diverse, public high school in California, where all students have been required to take chemistry since the school's founding in 1994. The authors highlight the following four beliefs and instructional practices that were instrumental in teachers' successful efforts to teach detracked chemistry classes: (1) teachers' true belief in a developmental conception of ability and intelligence; (2) a focus on an inquiry‐based pedagogical approach to chemistry foregrounding real‐world contexts; (3) a focus on teaching students study skills; and (4) a strong sense of community in the classroom, where students are held responsible for their own and each other's learning. To illustrate each of these findings, the authors select vivid examples from fieldnotes of classroom observations as well as interviews of teachers and students that make clear how teachers enacted and students experienced these elements in chemistry classrooms. © 2007 Wiley Periodicals, Inc. Sci Ed 91:683–709, 2007

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We present a new Monte Carlo lattice model to study the folding of two-dimensional heteropolymer chains. Previous lattice model studies of two-dimensional chains have been performed on square grids using predefined "move sets" of allowed moves. The motion of the polymer chain in these models is thus highly constrained. To add greater flexibility, we use a triangular lattice and allow the chain to choose its own moves. Physically unrealistic moves are prevented by including kinetic energy effects in the Metropolis algorithm. From the results, we can characterize all of the possible one-and two-monomer moves and sort them according to relative importance. Greater flexibility in the lattice model produces several significant and interesting physical consequences.