Instructionally Dense Literacy Practice in the Middle Grades: A Qualitative Study

This qualitative, practitioner inquiry examined how a group of novice and experienced middle-grade reading teachers integrated facets of instructional density (Pressley, Wharton-McDonald, & Mistretta-Hampston, 1997) into their practice. Instructional density is a descriptor of effective teaching whereby practitioners layer their instruction in individual lessons with other elements of the curriculum. This occurs in the planning of instruction as well as during dialogic exchanges with students that are the natural outcrop of instruction. The researcher’s role was to conduct a series of observations and post-observation reflections and provide coaching that helped participants generate understanding of instructional density and how it could be enacted. Through detailed vignettes, this study provides insights into (a) how instructional density is realized in the context of classroom teaching, (b) how differences in content knowledge inform the process of using instructional density, and (c) how practitioners negotiate meaning of instructional density through collaboration. The design of the study regarded professional collaboration as fundamental to improving practice. The descriptions herein are useful in considering how teachers learn to use their curriculum in new ways, ones that are more cohesive and efficient, and that acknowledge its interconnectedness. Advisor: Stephanie Wessel

Instructionally Dense Literacy Practice in the Middle Grades: A Qualitative Study

This qualitative, practitioner inquiry examined how a group of novice and experienced middle-grade reading teachers integrated facets of instructional density (Pressley, Wharton-McDonald, & Mistretta-Hampston, 1997) into their practice. Instructional density is a descriptor of effective teaching whereby practitioners layer their instruction in individual lessons with other elements of the curriculum. This occurs in the planning of instruction as well as during dialogic exchanges with students that are the natural outcrop of instruction. The researcher’s role was to conduct a series of observations and post-observation reflections and provide coaching that helped participants generate understanding of instructional density and how it could be enacted. Through detailed vignettes, this study provides insights into (a) how instructional density is realized in the context of classroom teaching, (b) how differences in content knowledge inform the process of using instructional density, and (c) how practitioners negotiate meaning of instructional density through collaboration. The design of the study regarded professional collaboration as fundamental to improving practice. The descriptions herein are useful in considering how teachers learn to use their curriculum in new ways, ones that are more cohesive and efficient, and that acknowledge its interconnectedness. Advisor: Stephanie Wessel

Bimodality in Damped Lyman alpha Systems

We report evidence for a bimodality in damped Ly systems (DLAs). Using [C II] 158 mu cooling rates, lc, we find a distribution with peaks at lc=10^-27.4 and 10^-26.6 ergs s^-1 H^-1 separated by a trough at lc^crit ~= lc < 10^-27.0 ergs s^-1 H^-1. We divide the sample into low cool DLAs with lc < lc^crit and high cool DLAs with lc > lc^crit and find the Kolmogorv-Smirnov probabilities that velocity width, metallicity, dust-to-gas ratio, and Si II equivalent width in the two subsamples are drawn from the same parent population are small. All these quantities are significantly larger in the high cool population, while the H I column densities are indistinguishable in the two populations. We find that heating by X-ray and FUV background radiation is insufficient to balance the cooling rates of either population. Rather, the DLA gas is heated by local radiation fields. The rare appearance of faint, extended objects in the Hubble Ultra Deep Field rules out in situ star formation as the dominant star-formation mode for the high cool population, but is compatible with in situ star formation as the dominant mode for the low cool population. Star formation in the high cool DLAs likely arises in Lyman Break galaxies. We investigate whether these properties of DLAs are analogous to the bimodal properties of nearby galaxies. Using Si II equivalent width as a mass indicator, we construct bivariate distributions of metallicity, lc, and areal SFR versus the mass indicators. Tentative evidence is found for correlations and parallel sequences, which suggest similarities between DLAs and nearby galaxies. We suggest that the transition-mass model provides a plausible scenario for the bimodality we have found. As a result, the bimodality in current galaxies may have originated in DLAs.Comment: Accepted for publication in the Astrophysical Journal 18 pages 14 figure