Teachers’ beliefs and classroom practices about their oral and written corrective feedback strategies in selected peri-urban and rural schools in Umguza district in Zimbabwe.
- Authors: Green , Flosie Florence
- Date: 2019
- Subjects: Teachers Classroom management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/17987 , vital:42001
- Description: The goal of the study was to examine teachers’ beliefs and classroom practices about their corrective feedback strategies in selected peri-urban rural schools in Umguza District in Zimbabwe, in order to draw up a Corrective Feedback model aimed at enhancing ESL proficiency among O’ level school pupils. The study has been necessitated by challenges which post O’ level students face when communicating in English at institutions of higher learning. The study used the mixed research approach, whereby both quantitative and qualitative methods of gathering data were used though the dominant approach was the qualitative approach. Data was collected through questionnaires, semi structured interviews, lesson observations and examination of pupils’ written exercises. The questionnaire was completed by twenty two teachers. Semi-structured interviews were held with six teachers from the selected schools, while nine lesson observations were done and eighty exercise books were scrutinized for the presence of written Corrective Feedback. Results obtained showed that teachers’ stated beliefs about corrective feedback were not always demonstrated in their classroom practices. Furthermore the study revealed that oral Corrective Feedback was not used consistently in addition to a lack of uniformity in both the usage and interpretation of written Corrective Feedback. Results obtained showed that teachers’ stated beliefs about Corrective Feedback were not always demonstrated in their classroom practices. In addition, the study also revealed that some teachers were not aware of the codes used in written Corrective Feedback and their meaning. The conclusion reached in this study was that vi there is need for a more informed and consistent usage of Corrective Feedback among teachers. In the light of this finding, a Corrective Feedback model was suggested to assist teachers apply Corrective Feedback more consistently and more productively. A number of recommendations were made at the conclusion of this study. Firstly, it was recommended that marking codes be availed to teachers and pupils before the beginning of the school calendar. The contents of the advisory chart included in this study could be given to pupils to copy onto the back of their exercise books to enable them to interpret the feedback which the teachers would have written. It was recommended that teachers familiarise themselves with the developments in the use of CF in the ESL classroom. At school level this could be done through staff development workshop, where teachers share experiences about what works and what does not work in the ESL classroom. This should be done in view of the existing problem of communicative incompetency bedevilling pupils nationally. Secondly it was recommended that teachers familiarise themselves with the developments in the use of CF in the ESL classroom. The final recommendation was that teachers adopt minimal marking in the form of codes in order to cut down on turnaround time as well as stimulate individual learner automatisation of knowledge.
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- Date Issued: 2019
English first additional language writing competency among grade 12 learners : the case of two Eastern Cape rural public schools
- Authors: Besman, Shirley
- Date: 2017
- Subjects: Competency-based education English language -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/6403 , vital:29656
- Description: Contextualized in the South African Language in Education Policy (LiEP) and the Curriculum and Assessment Policy Statement (CAPS), the study aimed at investigating the writing competency of EFAL Grade 12 learners in the two rural public schools. It was the researchers‘ hunch that the learners‘ socio-cultural conditions at which they learn EFAL are not taken into consideration by teachers and that hampers or impedes the development of language and writing. Further, the research sought to unearth the strategies and techniques used by teachers to teach writing in EFAL, and whether these facilitate the development of writing competency, that enhances better performance in other Grade 12 subjects taught through English as a Language of Learning and Teaching (LoLT). The study is informed by the socio-cultural theory, language acquisition theories, and the language learning theories. The study also drew from the writing strategies, writing in the curriculum, and second language learning discourses Framed in the interpretive paradigm and the qualitative approach, the research adopted a case study design. The sample of the study comprised of seven teachers of which two were EFAL teachers and five of these teach content subjects. Twenty four Grade 12 learners constituted the four Focus Groups. The data collection tools comprised of interviews, Focus Group Discussions (FGDs), observation and document analysis. Learners wrote essays and free writing exercises which formed transcripts for document analysis. The purposively selected teachers and the Grade 12 learners were granted interview questions in advance. The collected data was analysed and put under themes as determined by the study‘s research questions. Such themes included; challenges faced by learners when writing in EFAL, strategies used by teachers in teaching writing , perceptions of teachers and learners on learners‘ writing competency and the connection or linkage between learners‘ writing competency in EFAL and content subjects. Learners‘essays and free writing revealed that the learners have limited vocabulary in their FAL. Furthermore, the study made known that learners experience anxiety when they have to answer questions in English and that results in them being incompetent in writing in the target language. Other hindrances to EFAL writing that were revealed by the study included the detrimental effect of social media on the writing competency and lack of motivation to read for writing in English. In addition, the study established that there were teaching approaches that were employed by teachers when teaching writing which included the process writing and integration. Content subject teachers made known to the study that they were not teaching writing to the learners but assess them in essay writing and summaries as required by the school-based assessments in their respective subjects. It was also disclosed in the study that writing encompasses other language skills especially reading. The study also revealed that writing is a skill that is obligatory to be taught because it becomes beneficial to other subjects and that it enhances learners‘ writing for a variety of reasons. Overall, the study made known that there are complex circumstances that Grade 12 learners in rural public schools encounter when engaging in writing in the EFAL. The study concluded that although English could be perceived as a dominant language, it is embedded with multiplicity of challenges in the rural secondary schools where it is used as a LoLT. Such hindrances mostly find expression when learners have to engage in writing activities and encompass; lack of motivation, anxiety, limited vocabulary and the influence of social networks. The study recommended that the EFAL policy makers should not use a blanket approach on how EFAL should be taught but consider the demographic situations of the various sections of South Africa. The study also recommended that code switching which is practiced in bilingual classrooms appears inevitable and therefore should be formalized.
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- Date Issued: 2017
Synthetic analogues of marine bisindole alkaloids as potent selective inhibitors of MRSA pyruvate kinase
- Authors: Veale, Clinton Gareth Lancaster
- Date: 2014 , 2014-04-02
- Subjects: Alkaloids , Pyruvate kinase , Staphylococcus aureus , Antibiotics , Sponges -- South Africa , Imidazoles , Biological assay , Antibacterial agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4563 , http://hdl.handle.net/10962/d1020893
- Description: Globally, methicillin resistant Staphylococcus aureus (MRSA) has become increasingly difficult to manage in the clinic and new antibiotics are required. The structure activity relationship (SAR) study presented in this thesis forms part of an international collaborative effort to identify potent and selective inhibitors of an MRSA pyruvate kinase (PK) enzyme target. In earlier work the known marine natural product bromodeoxytopsentin (1.6), isolated from a South African marine sponge Topsentia pachastrelloides, exhibited selective and significant inhibition of MRSA PK (IC₅₀ 60 nM). Accordingly bromodeoxytopsentin provided the initial chemical scaffold around which our SAR study was developed. Following a comprehensive introduction, providing the necessary background to the research described in subsequent Chapters, this thesis has been divided into three major parts. Part one (Chapter 2) documents the synthesis of two natural imidazole containing topsentin analogues 1.40, 1.46, five new synthetic analogues 1.58—1.61, 2.104. In the process we developed a new method for the synthesis of topsentin derivatives via selenium dioxide mediated oxidation of N-Boc protected 3-acetylindoles to yield glyoxal intermediates which were subsequently cyclized and deprotected to yield the desired products. Interestingly we were able to demonstrate a delicate relationship between the relative equivalents of selenium dioxide and water used during the oxidation step, careful manipulation of which was required to prevent the uncontrolled formation of side products. Synthetic compounds 1.40, 1.46, 1.58—1.61 were found to be potent inhibitors of MRSA PK (IC₅₀ 238, 2.1, 23, 1.4, 6.3 and 3.2 nM respectively) with 1000-10000 fold selectivity for MRSA PK over four human orthologs. In the second part of this thesis (Chapter 3) we report the successful synthesis of a cohort of previously unknown thiazole containing bisindole topsentin analogues 1.62—1.68 via a Hantzsch thiazole synthesis. Bioassay results revealed that these compounds were only moderate inhibitors of MRSA PK (IC₅₀ 5.1—20 μM) which suggested that inhibitory activity was significantly reduced upon substitution of the central imidazole ring of topsentin type analogues with a thiazole type ring. In addition in Chapter 3 we describe unsuccessful attempts to regiospecifically synthesize oxazole and imidazole topsentin analogues through a similar Hantzsch method. As a consequence of our efforts in this regard we investigated three key reactions in depth, namely the synthesis of 2.2, 3.38, 3.40, 3.41 via α-bromination of 3-acetylindole and the synthesis of indolyl-3-carbonylnitriles 2.13, 3.45—3.47 and α-oxo-1H-indole-3-thioacetamides 3.48—3.51. The investigation of the latter led to the isolation and elucidation of two anomalous N,N-dimethyl-1H-indole-3-carboxamides 3.52 and 3.53. Finally the third part of this thesis (Chapter 4) deals with in silico assessment of the binding of both the imidazole and thiazole containing bisindole alkaloids to the MRSA PK protein which initially guided our SAR studies. In this chapter we reveal that there appears to be no correlation between in silico binding predictions and in vitro MRSA PK inhibitory bioassay data. Superficially it seems that binding energy as determined by the docking program used for these studies correlated with the size of the indole substituents and did not reflect IC₅₀ MRSA PK inhibitory data. Although this led us to computationally explore possible alternative binding sites no clear alternative has been identified.
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- Date Issued: 2014
Thermal decomposition of ammonium metavanadate
- Authors: Stewart, Brian Victor
- Date: 1972
- Subjects: Decomposition (Chemistry) , Solids -- Thermal properties , Ammonia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4503 , http://hdl.handle.net/10962/d1013274
- Description: The isothermal, endothermic, stepwise decomposition of ammonium metavanadate (AMV) in inert (argon or nitrogen), oxidising (air or oxygen) and reducing (ammonia) atmospheres as well as under high vacuum (pressure < IOn bar) conditions has been investigated. The reverse reaction, the isothermal recombination of V₂ 0₅ with ammonia and water vapour has also been investigated. The decomposition and recombination reactions were followed by continuously recording the mass loss of the sample with time using a Cahn R.G. Automatic Electrobalance. This enabled small samples ( ~ lOmg) to be used and consequently any self cooling of the sample during the decomposition was minimized. The intermediates and final products formed have been characterized by chemical analysis, X-ray powder diffraction studies, infrared spectroscopy and the mass loss involved in their formation. The changes in the physical properties of the samples during decomposition and recombination have been investigated by surface area measurements (using the BET method and krypton adsorption) and eIectron microscopy. Values for the enthalpy changes involved in the decomposition have been obtained by differential scanning calorimetry. The stoichiometry of the isothermal decomposition of ammonium metavanadate, under the various conditions of surrounding atmosphere has been discussed. Except for the later stages of the decomposition in ammonia, the results correspond well to the gradual reduction of the ratio of "(NH₄)₂ 0" to "V₂0₅" units from the original 1:1 ratio in ammonium metavanadate to pure "V₂0₅" with ammonia and water being evolved throughout the decomposition in the mole ratio of 2:1. The final product of the decomposition in vacuum, argon and air is "V₂0₅" and in ammonia, below 360°, V0₂. The kinetic parameters for each of the stages of the decomposition of AMV in each of the atmospheres studied have been determined. The mechanism of the first stage of the decomposition under the different conditions of surrounding atmosphere has been discussed from both the kinetic and the thermodynamic points of view. The absolute reaction rate theory has been applied to the decomposition in inert atmospheres enabling the formulae of the activated complexes formed during each stage to be calculated. It has also been shown that the detailed atomic movements occurring during the first stage of the decomposition in ammonia can be predicted from a knowledge of the stoichiometry of the reaction and of the detailed crystal structures of the starting and product materials. The kinetics and mechanism of the recombination of "V₂0₅" with ammonia and water vapour to form AMV have also been discussed in detail.
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- Date Issued: 1972