Exploring how teachers mediate learning of experimental techniques using fermentation and distillation of a traditional brew
- Authors: Paulus, Demetria
- Date: 2017
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/17637 , vital:22266
- Description: Physical Science is one of the subjects in which learners perform poorly in most Namibian schools. For instance, in ║Kharas region where the study was conducted, from 2010 to 2016, the overall performance has ranged between 20-40%. Furthermore, according to the results analysis report from the Directorate of National, Examination and Assessments (DNEA), from 2012 to 2016, the ||Kharas region was ranked 11th, 12th, 13th, 14th and 10th in the regional rankings. From the Examiner’s reports, the most poorly answered questions in the National Senior Certificate examinations are those that require learners to explain and show understanding. Additionally, the reports highlighted that learners lack practical skills or lack exposure to experiments and demonstrations to enhance their understanding (Namibia, 20142015). It is against this background that this study sought to explore how teachers mediate learning of experimental techniques using fermentation and distillation of a traditional brew. In particular, the study addressed the following sub-questions:1) what are Grade 11 Physical Science teachers’ perceptions and experiences on the inclusion of indigenous knowledge during Science lessons? 2) What factors influence Grade 11 Physical Science teachers’ perceptions and experiences on the inclusion of indigenous knowledge? 3) How do Grade 11 Physical Science teachers teach experimental techniques conventionally- fermentation and distillation? 4) How does the inclusion of a practical demonstration on making Ombike enable or constrain Grade 11 Physical Science teachers when explaining concepts on experimental techniques - fermentation and distillation? Thus, the focus was on conceptual understanding through linking content to the context of the learners. The study was underpinned by an interpretive paradigm whose focus is on understanding people’s worldviews. Within the interpretive paradigm, a mixed methods (Quant-QUAL methods) case study approach was employed in two sequential phases with Physical Science teachers at one secondary school in Keetmanshoop. Data were collected using document analysis (to strengthen my context). In the first phase, a questionnaire with closed-ended and open-ended questions was used to gather quantitative and qualitative data from 17 Physical Science teachers. Additionally, I conducted interviews with two Physical Science teachers from one Secondary School in Keetmanshoop who were selected based on their expertise, teaching experience and their qualifications. Quantitative data were analysed using frequency tables and graphs. For phase two, lesson and the practical demonstration observations were videotaped and transcribed inductively. Thematic analysis was used to analyse the qualitative data. The study was informed by Vygotsky’s (1978) socio-cultural theory with a focus on the mediation of learning, social interactions and learner engagement within the learners’ Zone of Proximal Development (ZPD) in conjunction with Shulman’s (1987) theory on pedagogical content knowledge (PCK). The findings of the study indicated that the majority of the Physical Science teachers were aware of and supported the inclusion of IK; on the other hand the teachers indicated some challenges that come with IK integration. Some teachers acknowledged the importance of IK, such as the enhancement of understanding, proving of theories, and arousal of interest and context relevance. However, some teachers felt that there are misconceptions in IK that can be carried into the classroom, IK resources like textbooks are not available, and IK is not integrated in the syllabus and examinations and lack of teacher training inter alia.The study recommends that the Ministry of Education, Arts and Culture especially the Division of Curriculum Planning and Development (NIED) needs to explicitly include IK in the Syllabus documents and suggest the inclusion of IK in the textbooks to the publishers to address these challenges. In order to enhance the teaching and learning with IK in Science, it is critical that teachers’ training workshops are conducted and IK resources are designed so that IK integration can be successfully implemented. For that to happen, it is recognized that the teachers’ PCK should be regularly upgraded through Continuous Professional Development (CPD) by the Subject Advisors (SA) so that the teachers are consistently guided on appropriate teaching methodologies and pedagogies about the inclusion of IK.
- Full Text:
- Date Issued: 2017
- Authors: Paulus, Demetria
- Date: 2017
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/17637 , vital:22266
- Description: Physical Science is one of the subjects in which learners perform poorly in most Namibian schools. For instance, in ║Kharas region where the study was conducted, from 2010 to 2016, the overall performance has ranged between 20-40%. Furthermore, according to the results analysis report from the Directorate of National, Examination and Assessments (DNEA), from 2012 to 2016, the ||Kharas region was ranked 11th, 12th, 13th, 14th and 10th in the regional rankings. From the Examiner’s reports, the most poorly answered questions in the National Senior Certificate examinations are those that require learners to explain and show understanding. Additionally, the reports highlighted that learners lack practical skills or lack exposure to experiments and demonstrations to enhance their understanding (Namibia, 20142015). It is against this background that this study sought to explore how teachers mediate learning of experimental techniques using fermentation and distillation of a traditional brew. In particular, the study addressed the following sub-questions:1) what are Grade 11 Physical Science teachers’ perceptions and experiences on the inclusion of indigenous knowledge during Science lessons? 2) What factors influence Grade 11 Physical Science teachers’ perceptions and experiences on the inclusion of indigenous knowledge? 3) How do Grade 11 Physical Science teachers teach experimental techniques conventionally- fermentation and distillation? 4) How does the inclusion of a practical demonstration on making Ombike enable or constrain Grade 11 Physical Science teachers when explaining concepts on experimental techniques - fermentation and distillation? Thus, the focus was on conceptual understanding through linking content to the context of the learners. The study was underpinned by an interpretive paradigm whose focus is on understanding people’s worldviews. Within the interpretive paradigm, a mixed methods (Quant-QUAL methods) case study approach was employed in two sequential phases with Physical Science teachers at one secondary school in Keetmanshoop. Data were collected using document analysis (to strengthen my context). In the first phase, a questionnaire with closed-ended and open-ended questions was used to gather quantitative and qualitative data from 17 Physical Science teachers. Additionally, I conducted interviews with two Physical Science teachers from one Secondary School in Keetmanshoop who were selected based on their expertise, teaching experience and their qualifications. Quantitative data were analysed using frequency tables and graphs. For phase two, lesson and the practical demonstration observations were videotaped and transcribed inductively. Thematic analysis was used to analyse the qualitative data. The study was informed by Vygotsky’s (1978) socio-cultural theory with a focus on the mediation of learning, social interactions and learner engagement within the learners’ Zone of Proximal Development (ZPD) in conjunction with Shulman’s (1987) theory on pedagogical content knowledge (PCK). The findings of the study indicated that the majority of the Physical Science teachers were aware of and supported the inclusion of IK; on the other hand the teachers indicated some challenges that come with IK integration. Some teachers acknowledged the importance of IK, such as the enhancement of understanding, proving of theories, and arousal of interest and context relevance. However, some teachers felt that there are misconceptions in IK that can be carried into the classroom, IK resources like textbooks are not available, and IK is not integrated in the syllabus and examinations and lack of teacher training inter alia.The study recommends that the Ministry of Education, Arts and Culture especially the Division of Curriculum Planning and Development (NIED) needs to explicitly include IK in the Syllabus documents and suggest the inclusion of IK in the textbooks to the publishers to address these challenges. In order to enhance the teaching and learning with IK in Science, it is critical that teachers’ training workshops are conducted and IK resources are designed so that IK integration can be successfully implemented. For that to happen, it is recognized that the teachers’ PCK should be regularly upgraded through Continuous Professional Development (CPD) by the Subject Advisors (SA) so that the teachers are consistently guided on appropriate teaching methodologies and pedagogies about the inclusion of IK.
- Full Text:
- Date Issued: 2017
Garnishee orders as a tax collection tool: a critical review of the South African and Zimbabwean models
- Authors: Nzombe, Kudzanayi
- Date: 2017
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/8082 , vital:21352
- Description: Taxation statues of most jurisdictions contain provisions that deal with defaulting taxpayers. The taxation statutes of Zimbabwe and South Africa have employed the concept of garnishee orders as a method of recovering tax. This method is codified in the respective taxation statutes under the guise of “third party appointments”, or simply “appointment of an agent”. This method is very convenient and expeditious for the tax collection authorities, namely, the Zimbabwe Revenue Authority (ZIMRA) and the South Africa Revenue Service (SARS). Other jurisdictions have also employed this method, with varying degrees of invasiveness into the taxpayers’ constitutional rights. The concept of garnishee orders can have negative constitutional implications for the taxpayers in both Zimbabwe and South Africa. In Zimbabwe, compared to South Africa, the tax collection field is not as developed in terms of jurisprudence and the legislation. There are lessons that Zimbabwe could learn from South Africa, considering that the latter has experienced more than two decades of constitutional democracy. Therefore, in order to identify areas for development, the two jurisdictions are critically reviewed, with particular attention to the legislative provisions and case law dealing with garnishee orders in the tax collection context. Approaches employed by other countries in relation to similar concepts and provisions are also analysed. The lessons learned from this analysis could suggest a less invasive method of recovering tax from defaulting taxpayers and an approach to be followed by the tax authorities, ZIMRA and SARS that would allow them to fulfil their responsibilities and mandate with taxpayer-friendly measures.
- Full Text:
- Date Issued: 2017
- Authors: Nzombe, Kudzanayi
- Date: 2017
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/8082 , vital:21352
- Description: Taxation statues of most jurisdictions contain provisions that deal with defaulting taxpayers. The taxation statutes of Zimbabwe and South Africa have employed the concept of garnishee orders as a method of recovering tax. This method is codified in the respective taxation statutes under the guise of “third party appointments”, or simply “appointment of an agent”. This method is very convenient and expeditious for the tax collection authorities, namely, the Zimbabwe Revenue Authority (ZIMRA) and the South Africa Revenue Service (SARS). Other jurisdictions have also employed this method, with varying degrees of invasiveness into the taxpayers’ constitutional rights. The concept of garnishee orders can have negative constitutional implications for the taxpayers in both Zimbabwe and South Africa. In Zimbabwe, compared to South Africa, the tax collection field is not as developed in terms of jurisprudence and the legislation. There are lessons that Zimbabwe could learn from South Africa, considering that the latter has experienced more than two decades of constitutional democracy. Therefore, in order to identify areas for development, the two jurisdictions are critically reviewed, with particular attention to the legislative provisions and case law dealing with garnishee orders in the tax collection context. Approaches employed by other countries in relation to similar concepts and provisions are also analysed. The lessons learned from this analysis could suggest a less invasive method of recovering tax from defaulting taxpayers and an approach to be followed by the tax authorities, ZIMRA and SARS that would allow them to fulfil their responsibilities and mandate with taxpayer-friendly measures.
- Full Text:
- Date Issued: 2017
Synthesis and characterization of titanium dioxide nanotubes using electrochemical anodization technique for solar cell applications
- Authors: Lupiwana, Mpheleki
- Date: 2017
- Subjects: Titanium dioxide Nanostructured materials Nanotubes
- Language: English
- Type: Thesis , Masters , Chemistry
- Identifier: http://hdl.handle.net/10353/11795 , vital:39107
- Description: High demand on energy conversion in dye-sensitized solar solar cells (DSSCs), requires development of well-organized TiO2 nanotube (TNT) structures because of their large surface area-to-volume ratio, superior lifetime and provision of optimal pathways for electron percolation. In this work TiO2 nanotube membranes with an average length of 2.40 μm and average pore diameter of 41.08 nm have been fabricated using electrochemical anodisation employing an organic electrolyte consisting of 0.5wt.percent NH4F + 3 vol percent H2O + Glycerol at an applied voltage of 60 V for 12 hours. The fabricated TNTs were annealed at different annealing temperatures. Scanning Electron Microscopy (SEM) showed that anodisation at these conditions yields nanotubes with periodic rings which present the roughness of the walls. Surface SEM images have revealed the presence of porous structures on the fabricated TNT membranes. Also evident from SEM cross-sectional images are multi-layered TiO2 nanotubes with top and bottom layers. The effect of annealing temperature on the structural, morphological and topographical has been investigated for TNTs. Surface SEM morphological analyses have revealed that the surface morphology of the annealed TNTs membranes changes with an increase in annealing temperature from 350°C to 650°C. The surface SEM analysis has revealed that as the annealing temperature increases the fabricated nanotubes deforms and collapses at annealing temperatures above 550°C. The TNTs annealed at 350°C have a modal pore size of 34.56 nm which is somewhat smaller compared to the TNTs annealed at 650°C with a modal pore size of 31.05 nm. Atomic Force Microscopy (AFM) topographical measurements have confirmed the presence of porous structure on the surface of the as-annealed TNTs with a modal pore diameter decreasing with increasing in annealing temperature. SEM-EDS analysis have revealed the presence of Ti, O and C and no other additional impurities. The presence of Ti and O confirms the successful electro-anodization of titanium metal sheets to TNTs. C must be due to glycerol electrolyte that got absorbed onto the TNTs structured during electro anodization. Structure investigation through X-Ray Diffraction (XRD) analysis has revealed that as-anodised TNTs have peaks at 2Ɵ positions 35.62°, 39.02°, 40.76°, 53.55°, 63.49°, 71.14°, and 76.71° belonging to the amorphous phase of TiO2. Additionally XRD analysis has revealed that for the annealed samples in the temperature range from 350°C to 450°C have peaks at 24.66° (101), 27.11° (110) belonging Anatase and Rutile phase of TiO2 respectively. Confocal Raman Spectroscopy (CRM) image analysis through a large area scan, and Raman depth profiling have also been used to evaluate the phase changes in TNTs annealed at different temperatures. CRM large area scan and depth profiling has revealed the presence of Anatase phase of TiO2 with Raman vibration modes at 142.37 cm-1, 199.04 cm-1, 394.67 cm-1,516.16 cm-1 and 639.29 cm-1 and the presence of some Rutile phase of TiO2 peaks with Raman vibration modes at 445.26 cm-1 and 612.07 cm-1. These findings were correlated to the XRD analysis, SEM analysis as well as AFM. In XRD the transformation of Anatase to Rutile phase was observed as the annealing temperature increased, that was also supported by SEM analysis whereby nanotube structures collapsed and deformed as annealing temperature increased due to phase transformation. In AFM pore diameter decreased as annealing temperature increases, which was also due to the effect of phase transformation observed in XRD and CRM. These findings showed that TiO2 nanotube membranes were successfully fabricated, which may have wide applications in the development of electronic materials for the solar devices.
- Full Text:
- Date Issued: 2017
- Authors: Lupiwana, Mpheleki
- Date: 2017
- Subjects: Titanium dioxide Nanostructured materials Nanotubes
- Language: English
- Type: Thesis , Masters , Chemistry
- Identifier: http://hdl.handle.net/10353/11795 , vital:39107
- Description: High demand on energy conversion in dye-sensitized solar solar cells (DSSCs), requires development of well-organized TiO2 nanotube (TNT) structures because of their large surface area-to-volume ratio, superior lifetime and provision of optimal pathways for electron percolation. In this work TiO2 nanotube membranes with an average length of 2.40 μm and average pore diameter of 41.08 nm have been fabricated using electrochemical anodisation employing an organic electrolyte consisting of 0.5wt.percent NH4F + 3 vol percent H2O + Glycerol at an applied voltage of 60 V for 12 hours. The fabricated TNTs were annealed at different annealing temperatures. Scanning Electron Microscopy (SEM) showed that anodisation at these conditions yields nanotubes with periodic rings which present the roughness of the walls. Surface SEM images have revealed the presence of porous structures on the fabricated TNT membranes. Also evident from SEM cross-sectional images are multi-layered TiO2 nanotubes with top and bottom layers. The effect of annealing temperature on the structural, morphological and topographical has been investigated for TNTs. Surface SEM morphological analyses have revealed that the surface morphology of the annealed TNTs membranes changes with an increase in annealing temperature from 350°C to 650°C. The surface SEM analysis has revealed that as the annealing temperature increases the fabricated nanotubes deforms and collapses at annealing temperatures above 550°C. The TNTs annealed at 350°C have a modal pore size of 34.56 nm which is somewhat smaller compared to the TNTs annealed at 650°C with a modal pore size of 31.05 nm. Atomic Force Microscopy (AFM) topographical measurements have confirmed the presence of porous structure on the surface of the as-annealed TNTs with a modal pore diameter decreasing with increasing in annealing temperature. SEM-EDS analysis have revealed the presence of Ti, O and C and no other additional impurities. The presence of Ti and O confirms the successful electro-anodization of titanium metal sheets to TNTs. C must be due to glycerol electrolyte that got absorbed onto the TNTs structured during electro anodization. Structure investigation through X-Ray Diffraction (XRD) analysis has revealed that as-anodised TNTs have peaks at 2Ɵ positions 35.62°, 39.02°, 40.76°, 53.55°, 63.49°, 71.14°, and 76.71° belonging to the amorphous phase of TiO2. Additionally XRD analysis has revealed that for the annealed samples in the temperature range from 350°C to 450°C have peaks at 24.66° (101), 27.11° (110) belonging Anatase and Rutile phase of TiO2 respectively. Confocal Raman Spectroscopy (CRM) image analysis through a large area scan, and Raman depth profiling have also been used to evaluate the phase changes in TNTs annealed at different temperatures. CRM large area scan and depth profiling has revealed the presence of Anatase phase of TiO2 with Raman vibration modes at 142.37 cm-1, 199.04 cm-1, 394.67 cm-1,516.16 cm-1 and 639.29 cm-1 and the presence of some Rutile phase of TiO2 peaks with Raman vibration modes at 445.26 cm-1 and 612.07 cm-1. These findings were correlated to the XRD analysis, SEM analysis as well as AFM. In XRD the transformation of Anatase to Rutile phase was observed as the annealing temperature increased, that was also supported by SEM analysis whereby nanotube structures collapsed and deformed as annealing temperature increased due to phase transformation. In AFM pore diameter decreased as annealing temperature increases, which was also due to the effect of phase transformation observed in XRD and CRM. These findings showed that TiO2 nanotube membranes were successfully fabricated, which may have wide applications in the development of electronic materials for the solar devices.
- Full Text:
- Date Issued: 2017
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