This study was an exploration of the relationship between classroom discourse and a high-stakes, standardized test, the Secondary Entrance Assessment (SEA), administered to students in Trinidad in their final elementary school year ("Standard 5"), with scores used to determine placement into secondary school. Classroom discourse was measured as represented in the oral and written language modeled to students by teachers and textbooks, and compared to the written language expectations implicit in the instructions and items on the SEA. Students' SEA scores were analyzed in relation to their teachers' language to determine if achievement was related to exposure to local/non-standard features of Trinidadian English. One outcome of this analysis was the creation of a survey developed to measure teachers' propensity for speaking Trini (Creole/dialect) or Trinidadian Academic English (standard English) in class by having them respond to audio clips. The survey was found to have acceptable reliability and concurrent validity. For the oral language investigation, 13 teachers were recorded as they led their class in one lesson, and an index of Trini usage (number of Trini utterances per 100 words) was calculated for each teacher. This index was used in an HLM model to determine if teachers' language was a predictor of their students' SEA scores. The distribution of the Trini index was positively skewed, M=1.1 and SD=1.25, indicating low usage of Trini. Trini usage was not found to be a significant predictor of students' 2008 SEA scores, but was found to be a significant predictor of the variation in SEA scores when these were aggregated by class. Similarly, there were few instances of Trini features in the examined textbooks. However, on the SEA, the only influence of Trini was the presence of dialect options used as distractors on two "fill in the blank" items, suggesting a mismatch between the features used in instructional language and the language expectations on the exam. In general, the low exposure to local features did not account for students' achievement on the SEA, but was positively related to the consistency of scores within a class. / text

Call number: LD2668 .T4 1965 W281

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The interannual variability of tropical climates, including the tropical Marine climate, is best reflected in the rainfall activity of a given area. The effects of such variability are manifested in a number of ways on the physical landscape. However, this study focused on the ways in which the variability of the rainfall received on the Caribbean island of Trinidad, influenced the resulting streamflow discharges for different basins on the island. Various techniques such as time series analysis and spectral analysis, were used to identify the physical mechanisms, both local and non-variations in the regimes, such that the effects of easterly waves were observed in the rainfall; the Madden-Julian wave was identified in both the precipitation and streamflow regimes; there was evidence of a faster 14-25 day oscillation; and finally, the migration of the Intertropical Convergence Zone was found to be quasi-periodic in nature.

Environments are changing rapidly, which renders many local populations susceptible to extinction unless they can adapt to these changes. Studies of rapid adaptation commonly document the evolution of individual traits. Overall adaptation however, is a function of fitness itself, rather than the individual traits that contribute to fitness. Although numerous studies provide evidence for the evolution of specific traits on contemporary time scales, no published studies of wild animal populations have examined the evolution of a major fitness component following environmental change. My research demonstrates that an introduced population of guppies (Poecilia reticulata) has adapted to its new environment in less than ten years (13-26 generations). This adaptation consists of several phenotypic traits that have changed in the expected direction. Most critically, the introduced population now has higher survival than its ancestral source population when both are tested together in the introduction site. These results show that important components of fitness can evolve rapidly in populations, and that this evolution might influence the persistence of populations in the face of environmental change.

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