Stars are one of the most frequently covered topics in introductory astronomy classes. From a constructivist framework, one must know what conceptions students bring with them to the classroom in order to effectively facilitate deep conceptual learning about stars. This study investigated the beliefs about stars that students hold when they enter an introductory astronomy course, and used that information to develop a concept inventory that can be used to assess those beliefs pre- and postinstruction.First, students' preinstructional beliefs were investigated through the use of student-supplied-response (SSR) surveys, which asked students to describe their ideas about topics such as what is a star, how is starlight created, how are stars formed, are all stars the same, and more. More than 2,200 students participated in this portion of the study during four semesters. Responses were inductively analyzed in an iterative process and coded for themes. Calculated frequencies show that although many students (80%) understand that stars are made of gas, a third to half of the participants (32-44%, depending upon the question) believe that starlight is created (or energy otherwise emitted) as a result of the star burning. Nuclear fusion, the true energy source in stars, is identified by fewer than 10% of the students. Interviews with seven volunteers confirmed that the responses seen on the SSR surveys were consistent with verbal explanations.The second portion of the study involved the design and testing of the Star Properties Concept Inventory. After item development and testing on Versions 1 and 2, interviews with 18 participants about their responses to Version 1, and an expert review by 26 volunteer astronomy instructors, Version 3 was created and tested during the Fall 2005 semester. Results from approximately 2,000 students who took Version 3 show that those students in an introductory astronomy course for nonscience majors increased their scores significantly over the semester, whereas a control group (students in an introductory earth science course for nonscience majors) showed no increase. These results support the purpose of this concept inventory to investigate the effectiveness of instruction on the topic of star properties and formation.

In the USA, science teachers are challenged by the National Science Education Standards (NSES) to "select teaching and assessment strategies that support the development of student understanding and nurture a community of science learners" (NRC, 1996, p. 30). While standards do not explicitly refer to constructivist learning theory, they are entirely consistent with the view that knowledge is a human construction, learning is based on prior knowledge, and students respond to their environment to build new understandings. Paralleling the NSES reforms, with their constructivist underpinnings, there is also a strong and often contradictory pressure on teachers to prepare students for national and state standardised tests. The need for teachers to balance these competing demands while trying to teach for understanding sets the context for this research.The purpose of this research has been to focus on "how" teachers determine students' understanding and "why" they employ the instructional and assessment strategies that they do. Interpretive case studies of five teacher participants from one school district are used to describe how these teachers teach for understanding in the face of the competing pressures of conforming to the NSES and preparing students for success on standardised multiple-choice achievement tests. These case studies are analysed to identify common themes and propositions about teaching for understanding.The teachers in this study used a variety of instructional and assessment strategies. Their choices of strategies made a difference in the degree of understanding that their students achieved. Frequently, the teachers' decisions were affected by their grasp of science concepts and ideas about how students learned. When teaching for understanding, these teachers preferred informal knowledge of student understanding to that obtained from standardised ++ / tests Although subjected to conflicting pressures regarding how teachers were able to disregard assessments that did not provide evidence of student understanding. This research has implications for the five teacher participants, myself as a researcher, the district as a whole and educators with an interest in implementing assessment strategies that foster student achievement for understanding.

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Doctor of Philosophy / Department of Physics / Nobel S. Rebello / Conventional wisdom has long advised that students’ learning is best supported by interaction with physical manipulative. Thus, in the physics laboratory, students typically spend their time conducting experiments with physical equipment. However, computer simulations offer a tempting alternative to traditional physical experiments. In a virtual experiment, using a computer simulation, students can gather data quickly, and measurement errors and frictional effects can be explicitly controlled. This research investigates the relative support for students’ learning offered by physical and virtual experimentation in the context of simple machines. Specifically, I have investigated students’ learning as supported by experimentation with physical and virtual manipulative from three different angles-- what do students learn, how do students learn, and what do students think about their learning. The results indicate that the virtual manipulative better supported students’ understanding of work and potential energy than the physical manipulative did. Specifically, in responding to data analysis questions, students who used the virtual manipulative before the physical manipulative were more likely to describe work as constant across different lengths of frictionless inclined planes (or pulley systems) and were more likely to adequately compare work and potential energy, whereas students who used the physical manipulative first were more likely to talk about work and potential energy separately. On the other hand, no strong support was found to indicate that the physical manipulative better supported students’ understanding of a specific concept. In addition, students’ responses to the survey questions indicate that students tend to value data from a computer simulation more than from a physical experiment. The interview analysis indicates that the virtual environment better supported the students to create new ideas than the physical environment did. These results suggest that the traditional wisdom that students learn best from physical experiments is not necessarily true. Thus, researchers should continue to investigate how to best interweave students’ experiences with physical and virtual manipulatives. In addition, it may be useful for curriculum designers and instructors to spend more of their efforts designing learning experiences that make use of virtual manipulatives.

This study is a systematic literature review on the role of models and representations in the teaching, learning and understanding of the atom and atomic concepts. The aim of the study is to investigate the role of different visual representations, what models and representations are used in the science classroom, how learners interpret different external representations of the atom, what mental models students construct, and how the representations can be used and designed for meaningful learning and teaching of the atom and atomic concepts.   In this systematic literature review, a combination of different databases was used to search for literature, namely ERIC, Scopus and Google Scholar. Some limiters were used to narrow down the returned results: the articles should be peer-reviewed and be published 1990-01-01 or later. Ten of the returned articles were included for individual analysis in the study.   The results of the study show that students often find concepts of atomic structure difficult and confusing. The abstract microscopic world of atoms cannot be seen with the naked eye, and models are therefore necessary and crucial educational tools for teaching atomic concepts in school. However, when using a model, it is important for the teacher to explain the rules of the model, and the advantages and limitations of the representation must be discussed. Analysis of the included articles revealed three types of representations used to represent atomic phenomena: two-dimensional static diagrams or pictures (e.g. a picture of the atom), three-dimensional videos or simulations (e.g. virtual reality simulations), and visual analogies (e.g. the Bohr planetary model of the atom). The use of simulations and interactive learning environments seem to have a positive effect on students’ learning. One of the studies, described in the articles included for analysis, showed that students appreciated the use of virtual reality simulations, since it made abstract concepts easier to understand when they could be visualized.

In many ways, higher educational systems in the United States are the most extraordinary in the world. Students come from all over to study in our institutes of higher learning. As our search for an explanation of how to facilitate student learning continues, the goal of this dissertation was to examine the heavily under-researched area of teacherstudent relationships as they relate to student understanding. Using the existing body of instructional communication research, the Student Understanding Model (SUM) is proposed and tested. Data collected from 302 undergraduate students was used to test the SUM. Results provide empirical support that relational messages account for approximately 26% of the variance in student understanding. Conclusions and implications from the current study were discussed.

Research indicates that many elementary students do not comprehend that the equal sign is an indication that an equality relation exists between two structures. Instead, they perceive the equal sign as an indication that a particular procedure is to be performed. As students mature, and as their exposure to the equal sign and equality relations in multiple contexts increases, most obtain the ability to interpret the equal sign as an indicator of an equivalence relation. Incorrect usages of the equal sign, however, by post-algebra students indicate a tendency for students to regress back to a comprehension of the equal sign as an operator symbol or to ignore the equal sign altogether. The purpose of this project was to develop an instrument that is relevant to objectives associated with the interpretation of the equals relation, and to perform a test reliability analysis to assess measurement reliability and construct validity for the instrument. The model that was utilized to develop items for the instrument followed a general item development and validity assessment model proposed by Cangelosi. This model requires an iterative process that includes a peer review of objectives and instrument items by a panel of experts and a revision of the items based upon recommendations from the panel. A pilot test was synthesized from the revised items and administered to a group of subjects, and an instrument reliability analysis and an item efficiency analysis were performed. The quantitative and qualitative data obtained from this process were used to create the 18-item instrument entitled, Wheeler Test for Comprehension of Equals. The researcher recommends further validity assessments for the instrument across multiple settings and subject groups.

The purpose of this study is to examine philosophical hermeneutics as a referent for student understanding of Nature-of-Science (NOS) concepts. Rather than focus on a prescriptive set of canons used in addressing NOS pedagogy in K-12 schools, this study seeks to explicate a descriptive set of principles based on Hans Georg-Gadamer’s theory of interpretation that has the potential for developing dispositions necessary for understanding. Central among these are the concepts of fore-structure, prejudice, temporal distance, and history of effect, all of which constitute part of the whole of the hermeneutic circle as envisaged by Gadamer. As such, Gadamer’s hermeneutics is contrasted with Cartesian epistemology and its primacy of method, the Enlightenment’s prejudice against prejudice, the modernist/progressive tendency to consider all situations as problems to be solved by relegating all forms of knowledge to techné, and the subjective nature of interpretation inherent in a hermeneutics of suspicion. The implication of such a conceptual analysis for NOS pedagogy is that student understanding is considered not so much as a cognitive outcome dependent on a series of mental functions but rather as an ontological characteristic of Dasein (being-human) that situates learning in the interchange between interpreter and text. In addition, the philosophical foundations implicit in addressing student understanding of NOS found in many curricular reform efforts and pedagogical practices in science education are questioned. Gadamer’s hermeneutics affords science education a viable philosophical framework within which to consider student understanding of the development of scientific knowledge and the scientific enterprise.

This dissertation examines two broad topics -- emission line properties of active galactic nuclei (AGN) and the effect of hands-on, integrated science courses on student understanding of astronomy. To investigate trends in overall properties of emission lines in AGN, we apply principal component analysis (PCA) to the fluxes in the H [beta] - (O III) region of a sample of 9046 spectroscopically-identified broad-line AGN from the Sloan Digital Sky Survey (SDSS) Data Release 5 with a redshift range of 0.1 < z < 0.56. After performing independent spectral PCA on subsets defined effectively by their (O III) equivalent width (EW), we find only the weakest (O III) objects retain the optical Fe II - (O III) anticorrelation and the correlation of EW[subscript O III] with H [beta] linewidth that have previously been found in high-luminosity AGN. The objects with strongest EW[subscript O III] do not differ from the entire data set significantly in other spectral and derived properties, such as luminosity, redshift, emission line shapes, Eddington ratio, continuum slope, and radio properties. However, our findings are consistent with previous suggestions that (O III) emission is primarily a function of covering factor of the narrow-line region. To investigate the other side of the Fe II - (O III) anticorrelation, we examine the effect of changes in the gas-phase abundance of Fe on observed variation in Fe II. Using AGN spectra from the SDSS in the redshift range of 0.2 < z < 0.35, we measure the Fe/Ne abundance of the narrow-line region (NLR) using the (Fe VII)/(Ne V) line intensity ratio. We find no significant difference in the abundance of Fe relative to Ne in the NLR as a function of Fe II/H [beta]. However, the (N II)/(S II) ratio increases by a factor of 2 with increasing Fe II strength. This indicates a trend in N/S abundance ratio, and by implication in the overall metallicity of the NLR gas, with increasing Fe II strength. We propose that the wide range of Fe II strength in AGN largely results from the selective depletion of Fe into grains in the low ionization portion of the broad-line region. We utilize photoionization models to show that the strength of the optical Fe II lines varies almost linearly with gas-phase Fe abundance, while the ultraviolet Fe II strength varies more weakly, as seen observationally. After examining the emission line properties of large samples of fairly typical AGN, we investigated the newly expanded regime of low-mass AGN (M[subscript BH] [less than or approximately equal to] 10⁶ M[subscript sun]) with respect to their emission line properties at a smaller scale. We utilize the high spectral resolution and small aperture of our Keck data of 27 low-mass AGN, taken with the Echellette Spectrograph and Imager, to isolate the NLRs of these low-mass black holes. Some of these low-luminosity objects plausibly represent examples of the low-metallicity AGN described by Groves et al. (2006), based on their (N II)/H[alpha] ratios and their consistency with the Kewley & Ellison (2008) mass-metallicity relation. We also find that these low-mass AGN have steeper UV continuum slopes than more-massive AGN based on their He II/H[beta] ratio. Overall, NLR emission lines in these low-mass AGN exhibit trends similar to those seen in AGN with higher-mass BHs, such as increasing blueshifts and broadening with increasing ionization potential. Additionally, we see evidence of an intermediate line region whose intensity correlates with L/L[subscript Edd] in these objects, as seen in higher-mass AGN. We highlight the interesting trend that, at least in these low-mass BHs, the (O III) EW is highest in symmetric NLR lines with no blue wing. This trend of increasing (O III) EW with line symmetry could be explained by a high covering factor of lower ionization gas in the NLR. We also investigate effective methods for teaching astronomy and connections between astronomical topics in student learning and understanding. After developing the curriculum for a hands-on, learner-centered astronomy course (Hands-on-Science, hereafter HoS) aimed at pre-service elementary teachers, we measure student performance in HoS compared to traditional, large lecture courses (hereafter Astro101). We utilize distractor-driven multiple choice assessments in order to quantitatively assess student understanding and evaluate the persistence or correction of common misconceptions in astronomy. We find that for the topics included in the HoS curriculum, HoS students have a higher average post-test score, and higher normalized gains, than the Astro101 students. We cannot pinpoint the exact cause of this student achievement because of the multitude of nontraditional practices incorporated into the HoS implementation. Increased time-on-task, a classroom environment structured around student discussion, or focus on conceptual understanding could each be key factors in the high achievement of HoS students. We conclude that the HoS students are better prepared in astronomy for their future careers as elementary school teachers by HoS courses than they would have been in traditional, introductory astronomy courses. When we compare directly between topics covered in both HoS and Astro101, we find that HoS students have normalized gains that are a factor of 2-4 higher than those of Astro101 students. Therefore, we conclude that curricula similar to the HoS approach would benefit Astro101 students as well, particularly for topics which are most impacted by the HoS method, such as Moon phases and seasons. Lastly, a PCA of the changes in HoS student scores reveals that there is very little systematic student variation apart from the trends apparent in the mean changes in the sample. Thus, we do not find groupings of questions that some subsets of students systematically learn more readily than others. Another way to interpret this result is that the HoS curriculum and methodology indiscriminately help all kinds of pre-service elementary teachers, despite presumptive differences in their own learning styles and strengths. / text

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