This action research project examines first year science teachers’ conceptions of scientific inquiry and their challenges in implementing inquiry-based lessons. Classroom observations and interviews ...represent two first-year primary school science teachers’ conceptions of science as inquiry. Because the current educational landscape emphasizes inquiry-based learning as a foundation of science education, teacher-training in Singapore focuses on augmenting the quality of inquiry-based science lessons. Through a mandatory reduced workload, first-year primary school science teachers can focus on transitioning from being student teachers to full-time teachers. A video of each teacher’s lesson was analysed using the EQUIP (Electronic Quality of Inquiry Protocol) instrument. Data analysis of the interviews involved a process of a priori coding based on the essential features of inquiry as well as grounded theory to expose the challenges the teachers faced in their enactment of inquiry-based instruction. Findings suggest that the two first-year teachers formed conceptions of inquiry through their teacher training programs. The teachers revealed three key considerations that affected their practice of inquiry: (1) assessment demands, (2) lack of resources and (3) lack of time to plan and to teach inquiry lessons. Findings in this action research project provide salient implications for other Asian countries which need to improve in-service teacher professional development programs in order to successfully enactment inquiry-based instruction.
Many efforts have been made to reach educational equity, especially to reduce mathematics and science achievement gaps by students’ socioeconomic status. Across countries, educators strive to reform ...traditional teacher-centered instructional approaches to more student-centered/inquiry-based instruction to improve equity in education. In this context, this study examines whether relationships between socioeconomic status and scientific or mathematical literacy are moderated by student-centered instruction. Ten countries covering a wide range of achievement levels as well as equity in education are selected for an international comparison. A linear regression analysis is applied to student achievement, equity, and frequency of student-centered instruction data from the PISA 2012 and PISA 2015. We find mixed results: As student-centered instruction is offered more frequently, the gap in mathematical and scientific literacy between low and high socioeconomic status is generally narrowed or maintained. In most countries, students’ mathematical and scientific literacy scores are expected to decrease across all socioeconomic status as student-centered instruction is given more frequently. The findings necessitate further scrutiny of how teachers implement student-centered instruction in various educational systems. This further research need to consider the complexity of implementation related to sociological and pedagogical aspects.
This dissertation aims to investigate the characteristics of generative science learning environments through students’ perceptual and teachers’ epistemic changes. Recent research studies in science ...education have paid attention to investigating students’ perceptual and teachers’ epistemic changes because changes give a legitimate sense of how to create authentic practice-based classrooms. Since the new science standards have emphasized students’ engagement in science and engineering practices, supporting students’ involvement in the practices is a critical issue in science education. In light of this, creating generative learning environments is essential. Students in generative classrooms develop conceptual understandings through epistemic practices such as translation, dialogic interaction, and argumentation. These epistemic practices allow students to learn science through the culture of science (e.g., asking questions to clarify ideas, designing scientific experiments, drawing conclusions through discussion).This dissertation consists of two research studies each addressing an essential component of generative learning. The first study exhibits how students perceive their learning environments. Two dialogic interaction factors, experience with and value of dialogic interaction, were developed to examine students’ views on learning environments. The Practical Epistemology in Science (PESS; Villanueva, Hand, Shelley, & Therrien, 2017) was used to construct the two dialogic interaction factors. A total of 5,709 middle school students who were taught by 23 Mathematics and Science Partnership project (MSP) teachers provided responses to the PESS questionnaires every Spring semester from 2015 through 2017. By utilizing Rasch modeling, a validity of two factors was verified. The findings highlight how classroom epidemic climates can be examined through students’ perceptions about dialogic interaction.The second study addresses the patterns of changes in teachers’ epistemic orientations for knowledge generation and teaching practices. The 23 participating MSP teachers took the Epistemic Orientation Survey (EOS, Suh, 2017) which was collected at six different points for three years from 2015 to 2017. Teacher implementation levels were measured by the researcher once a year for the three years. Through utilizing Longitudinal Cluster Analysis, three types of teacher profiles - fast adopters, slow adopters, and struggling adopters - were created. Fast adopters were early adopters, who shifted their epistemic orientation within 6 months of the project experience and continuously developed their teaching practices. Slow adopters were late adopters, who shifted their epistemic orientation and teaching practices in their second year of the project. Struggling adopters hardly showed any big changes in epistemic orientation and teaching practices.This dissertation is distinguished by taking a more encompassing focus on learning environments. Unlike many studies which usually focus on investigating classroom learning environments solely through students’ changes, this study examines the characteristics of generative learning environments through both, students’ and teachers’ changes. These multiple angles on classroom learning environments provide a better understanding of how generative learning environments are created and what learning experiences students need to engage in to develop positive perspectives on learning environments.
This study investigates two latent constructs (Engagement and Value) of dialogic interaction to examine the epistemic climate. Since the new reform movement emphasizes creating generative learning ...environments, it is important to examine whether a classroom promotes students’ knowledge generation or limit students’ epistemic growth through rote memorization. At this point, it is inevitable to focus on dialogic interaction (one of the epistemic practices), because how students engage with and view dialogic interaction provides meaningful information about the epistemic climate. By employing Rasch modeling, this study tested a statistical validity of two latent constructs of dialogic interaction. The findings in this study highlight that the two latent constructs are theoretically and statistically valid and can be used to gauge the epistemic climate through students’ engagement with and value of dialogic interaction. While understanding the epistemic climate cannot solely occur through a single perspective, this study plays a significant role in adding a valid instrument. Such instruments help researchers comprehend the epistemic features of learning environments and provide a practical way to reflect students' lived experiences to learn about the overall atmosphere of the learning environment.
This correction stands to correct Fig. 1 and Table 4 in the original article. This correction is due to Fig. 1 not having the red circles showing the strength of the socioeconomic gradient mean ...performance of the 10 selected countries. Additionally, some coefficients in Table 4 were not interpretable, which should be corrected.
Hemicellulose is the next most abundant plant cell wall component after cellulose. The abundance of hemicellulose such as xylan suggests that their hydrolysis and conversion to biofuels can improve ...the economics of bioenergy production. In an effort to understand xylan hydrolysis at high temperatures, we sequenced the genome of the thermophilic bacterium Caldanaerobius polysaccharolyticus. Analysis of the partial genome sequence revealed a gene cluster that contained both hydrolytic enzymes and also enzymes key to the pentose-phosphate pathway. The hydrolytic enzymes in the gene cluster were demonstrated to convert products from a large endoxylanase (Xyn10A) predicted to anchor to the surface of the bacterium. We further use structural and calorimetric studies to demonstrate that the end products of Xyn10A hydrolysis of xylan are recognized and bound by XBP1, a putative solute-binding protein, likely for transport into the cell. The XBP1 protein showed preference for xylo-oligosaccharides as follows: xylotriose > xylobiose > xylotetraose. To elucidate the structural basis for the oligosaccharide preference, we solved the co-crystal structure of XBP1 complexed with xylotriose to a 1.8-Å resolution. Analysis of the biochemical data in the context of the co-crystal structure reveals the molecular underpinnings of oligosaccharide length specificity.
Background:Caldanaerobius polysaccharolyticus is a thermophile with a hemicellulose utilization gene cluster.
Results: The cluster is induced by xylan. The ligand-binding cleft of XBP1 is optimized for binding xylotriose.
Conclusion: This gene cluster encodes all of the proteins required to degrade xylan, transport the fragments, and metabolize them via the pentose-phosphate pathway.
Significance: This gene cluster could be designed as a cassette to impart a capacity for utilizing hemicellulose.
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