The systematic investigation of the x-ray diffraction symmetry of scapolites covering the whole range of solid solution show that all scapolites possess space group P4(2)/n, except the pure end-members, marialite and meionite, which will possess space group I4/m, if they exist. The intensity of the weak superlattice reflections violating the body-centred symmetry, continuously increases from zero at the marialite end-member as Me% increases, reaches a maximum around 37%+/-2% Me then approximately symmetrically decreases to 75% Me followed by a slower decrease to zero at the meionite end-member. Hence, all the intermediate scapolites of the marialite-meionite series actually have a pseudosymmetric structure, i. e., a pseudobody-centred structure, and as the chemical composition approaches both end-members, the scapolite structure approaches the structure with a body-centred lattice. The weak super-lattice reflections are directly related to the following two correlated factors: (1) the relative order-disorder of A1 and Si distribution in the tetrahedral framework, and (2) the structural distortion from the body-centred symmetry. Accompanied with the above facts is the systematic deviation of cell dimensions from the linear regression in such a way that the further the structure deviates from the body-centred symmetry, the smaller the cell volume and the a(o) become relative to the evaluated one from the linear regression. Scapolites are regarded as a continuous, perfect solid solution with a long-range disordering, and unlikely to be composed of submicroscopic twins or different domains. The structural analyses and refinements of three scapolites (ON8, 20% Me; XL, 52% Me; ON45, 93% Me) have been carried out by using 3-dimensional intensity data collected by integrated precession film techniques (ON8, ON45) and an automated single-crystal diffractometer (XL), and using the full-matrix least0squares method. The result has clarified the ambiguities arising from the previous studies and showed that the crystal structure is essentially continuous along the marialite-meionite series, with a slight structural variation as a function of chemical composition and ordering of Al, Si. Several important quantitative relationships regarding the crystal structure and crystal chemistry of the scapolite solid solution series have been established, namely, (1) the relationship between the superlattice intensity r(ΣI(h+k+l=2n+1)/ΣI(h+k+l=2n)) and the chemical index % Me. (2) the exponential relationship between the superlattice intensity ration r and the atomic displacement from the mirror plane consistent with the space group I4/m. (3) The linear relationship between the superlattice intensity ratio r and the difference of Al occupancy between T2 and T3 sites. (4) The Al occupancy (%) of tetrahedral sites as a function of the chemical composition of scapolites. The ordering of Al-Si, the c-axis displacement of (Ca, Na), the tilting of CO3 and the relative amount of CO3 and Cl in the same scapolite are all inter-related. The mechanism to cause all such related structural phenomena and even the abnormal stoichiometry of scapolite can all be interpreted in terms of the internal strain created by the two greatly different anions, Cl- and CO3-,sharing the same set of equivalent sites. / Thesis / Doctor of Philosophy (PhD)

Schools face a great challenge in recruiting and retaining quality teachers, given the documented importance of, variability in, and difficulty observing and predicting teacher quality. One option schools have is to identify what more effective teachers do and use that information to train less effective teachers to get better. Unfortunately, there is little empirical support for much traditional teacher training, as measured by gains in student test scores. Models of collaborative, team-based learning – such as Professional Learning Communities and Japanese lesson study – have been widely touted, and there is some evidence that they may be effective in certain contexts. Economic theory suggests this could be because of peer monitoring, peer pressure, specialization, knowledge-sharing, or market failure in pre-service training, particularly if learning to teach is primarily experiential. However, not all collaboration is good due to concerns about free-riding and substituting for more productive individual activity, so unbridled enthusiasm for collaborative professional development may need to be tempered. This dissertation examines the effectiveness of a specific form of teacher collaboration in the form of inquiry teams, groups of teachers and administrators jointly engaged in action research projects with the aim of uncovering innovative instructional strategies and sharing effective approaches. It takes advantage of the phase-in of teams, eventually to all teachers in a large, urban school district in the northeastern United States from 2007-2010 to estimate the results of three natural experiments using difference-in-differences and instrumental variables approaches. The effects of teamwork on teacher value-added, teacher retention, and student test scores are small and sensitive to year, specification, and outcome, although results are mostly positive and occasionally statistically significant, suggesting that overall effects are potentially positive but modest at best. Further examination of heterogeneity and four qualitative case studies of teams suggest that small average effects mask considerable differences in team processes, and that under certain conditions, inquiry team work may be far more effective. A cost analysis reveals that, although it is costly to do inquiry work well, given the low-intensity of average treatment and the large number of students affected, the benefits of inquiry work could exceed the costs if the policy were more targeted. Overall, the policy recommendation is to temper unqualified enthusiasm about teacher collaboration, as without appropriate structures and supports it has little measurable effect on the outcomes examined here. As a policy lever, a universal mandate to participate on collaborative inquiry teams is unlikely to be effective or pass a cost-benefit test. Nonetheless, smaller-scale, higher intensity forms of collaboration that allow for more active leadership support and participation may be more promising, and more cost-effective than alternative forms of professional development, particularly for some sub-groups of teachers such as those in their first year of teaching.

Specific to the recommendation of the National Council of Teachers of Mathematics (1980) to identify and analyze problem solving strategies and the settings in which the development of these strategies could be optimized, this study is a compilation of three case studies which describe what elementary school children say and do when solving verbal mathematics problems in small groups. Persuant to this goal, three four-member groups were selected and asked to reach a consensus within each group on the solution to a variety of routine and non-routine problems. In this relatively unstructured setting, transcriptions of verbal interactions, written records of all computations, and observer notes were compiled for each group. The resulting identification and description of the problem solving behaviors which occurred were analyzed in terms of two broad interactive functions by which children seek to understand verbal problems: the construction of mental representations or physical displays of the problems and the evaluations of these constructions. Representations, in this perspective, are constructed at two levels: a contextual level at which the problem situation is linguistically interpreted and a structural level at which a statement of a problem underlying mathematical structure is defined. Evaluations also occur which allow group members to monitor their understanding and direct the course of the problem solving effort. The findings indicate that intermediate aged children when solving problems in small groups display general patterns of behavior. These patterns of behavior include: the manner in which the groups approach and effectively isolate the contextual elements of a verbal problem, the propensity of groups to change the mode in which a problem is represented by utilizing manipulatives, diagrams, tables and other physical displays, and the manner in which groups monitor the course of problem solving and reach consensuses on solution proposals. Within this general pattern, however, specific subject and task variables characterize individual groups, affecting both the group interaction and the incidence of specific problem solving behaviors. These findings suggest practical classroom applications for group problem solving formats in the elementary school classroom. Additional research, however, must provide the link between group problem solving and individual performance.

published_or_final_version / Psychology / Master / Master of Philosophy

Information technology has played several important roles in group decision making, such as communication support and decision support. Little is known about how information technology can be used to persuade members of a group to reach a consensus. In this dissertation, I aim to address the issues that are related to the role of visual representation technology (VRT) for persuasion in a forecasting context. VRTs are not traditional graphical representation technologies. VRTs can select, transform, and present data in a rich visual format that facilitates exploration, comprehension, and sense-making. The first study investigates conditions under which teams are likely to increase the use of VRTs and how the use of VRTs affects teams' consensus development and decision performance. The second study evaluates the effects of influence types and information technology on a choice shift. A choice shift is the tendency of group members to shift their initial positions to a more extreme direction following discussion. A choice shift is also called group polarization. To complement my first two studies, I conduct a laboratory experiment in my third study. I explore the effect of VRTs and team composition on a choice shift in group confidence.

The current understanding of students’ group metacognition is limited. The research on metacognition has focused mainly on the individual student. The aim of this study was to address the void by developing a conceptual model to inform the use of scaffolds to facilitate group metacognition during mathematical problem solving in computer supported collaborative learning (CSCL) environments. An initial conceptual framework based on the literature from metacognition, cooperative learning, cooperative group metacognition, and computer supported collaborative learning was used to inform the study. In order to achieve the study aim, a design research methodology incorporating two cycles was used. The first cycle focused on the within-group metacognition for sixteen groups of primary school students working together around the computer; the second cycle included between-group metacognition for six groups of primary school students working together on the Knowledge Forum® CSCL environment. The study found that providing groups with group metacognitive scaffolds resulted in groups planning, monitoring, and evaluating the task and team aspects of their group work. The metacognitive scaffolds allowed students to focus on how their group was completing the problem-solving task and working together as a team. From these findings, a revised conceptual model to inform the use of scaffolds to facilitate group metacognition during mathematical problem solving in computer supported collaborative learning (CSCL) environments was generated.

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In order to enhance academic achievement it is necessary to implement a teaching strategy which provides students with tools needed to improve classroom performance. This study will produce data showing whether the implementation of "Indentifying Similarities and Differences" is an effective teaching strategy.

The purpose of this three-essay dissertation was to expand knowledge and theory regarding soft systems methodologies (SSMs) and data visualization approaches in business, engineering, and other social sciences. The first essay depicts a bibliometric analysis study of the historic impacts of SSM from 1980-2018 on business, engineering, and other social sciences fields. This study found 285 articles that described or employed SSM for research and included outcomes such as top SSM authors, author citation impacts, common dissemination outlets, time-bound distribution of publications, and other relevant findings. This study provided a picture of who, what, why, when, and where SSM has had the greatest impact on academic thought and practice. The second essay presents research on the academic impact of Systemigrams, an associated data visualization approach, finding examples of conceptual or research development that employed Systemigrams to depict complex problem situations. Recommendations for improvement of designing these data visualizations to increase their field use resulted from this study. The final essay leverages a selection of the articles as use cases to produce a grounded theory study to identify phenomena that arose from the use of SSM for operations and firm strategy research. This study identified two broad themes including (i) scope, structure, and process challenges and (ii) performance and evaluation limitations. These themes were explained by six patterns that emerged from the publications. Each produced change recommendations for SSM process, practice, and reporting to support its continued viability and adoption in business and operations research.

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