Patterns of Student Mobility among English Language Learner Students in Arizona Public Schools. Summary. Issues & Answers. REL 2010-No. 093.
Issues & Answers is an ongoing series of reports from short-term Fast Response Projects conducted by the regional educational laboratories on current education issues of importance at local, state, and regional levels. Fast Response Project topics change to reflect new issues, as identified through lab outreach and requests for assistance from policymakers and educa-tors at state and local levels and from communities, businesses, parents, families, and youth. All Issues & Answers reports meet Institute of Education Sciences standards for scientifically valid research. views or policies
School Choice and Stratification in a Regional Context: Examining the Role of Inter-District Choice
Despite the growing popularity of interdistrict choice plans over the past decade, the policy assumptions underlying their adoption have been subjected to very little empirical research. This study situates school choice within one metropolitan region, Denver, and examines the ways in which choice patterns relate to existing patterns of stratification between school districts. This regional focus offers insight into the patterns of interdistrict choice and the influence these patterns have on equity within a metropolitan region. Findings from this study indicate that relatively higher income students were more likely to take advantage of interdistrict choice, and that choice was more often used by students to exit from a less advantaged context (as measured by socioeconomic status) to a relatively more advantaged one. The article concludes with recommendations for policymakers in designing more equity-minded choice policies.
Control of the homopause level
Abstract This paper reviews the hypothesis that internal gravity wave breaking in the factor responsible for upper atmosphere turbulence generation and control of the number density at the homopause level. Available data from Mars and Earth support the hypothesis, originally introduced by Lindzen, that breaking thermal tides are responsible for the necessary turbulence. The lowest-order, equatorially trapped, westward-propagating diurnal tidal mode is the primary cause on the Earth, and lower-order westward-propagating semidiurnal modes are the primary cause on Mars. The frequencies and vertical wavenumbers of the responsible modes determine the eddy diffusion coefficients; energy density is only indirectly involved by determining which modes can break. A general scale relationship between tidal heating and velocity amplitude can be used to assess the breaking potential of tidal modes, and is used here as the basis for arguing that the number density at the Martian homopause is likely to have been stable over much of geologic time. Difficulties with this approach arise in the cases of Venus and Titan because of their peculiar zonal winds. For Jupiter and Saturn, internal gravity waves generated by nontidal mechanisms probably control the homopause.