Task-Based Learning (TBL) has been shown to be effective in science education, but its application in Rwandan chemistry classes remains under-explored. This study examine classroom practices and experiences while TBL is being implemented in Rwandan secondary school chemistry classrooms. We conducted classroom observations to eight teachers from eight schools comprising 163 students in the control group and 206 students in the experimental group, making a total of 369 students. Interviews were conducted exclusively with students and teachers in the experimental group to gather information related to the use of TBL. Our findings revealed a shift towards a more student-centerd learning environment. TBLincreased student-to-student discussions by 26

Herein we report the zwitterionic pentagonal bipyramidal oxidorhenium(V) complex trans -[ReOI 2 (bpp)] where bpp is (1E,3E)-1,3-bis(pyrimidin-2-ylimino)propan-2-ide anion. The complex trans -[ReOI 2 (bpp)] was unusually formed from the reaction of trans -[ReOI 2 (OEt)(PPh 3 ) 3 ] with 2-aminopyrimidine in propan-2-ol in the presence of triethylamine (Et 3 N). The anionic ligand bpp was formed by oxidorhenium(V)-catalysed dehydroxylation of propane-2-ol followed by condensation with 2-aminopyrimidine, and coordinates to the [ReO] 3+ core as tetradentate N-donor chelate. A few numbers of pentagonal bipyramidal complexes are known for oxidorhenium(V), and the complex trans -[ReOI 2 (bpp)] is another example. The complex was analyzed by 1 H NMR, IR, UV-visible and single crystal X-ray crystallography. In addition, density functional theory (DFT) was also studied.

The aim of this study is to investigate the impacts of improvised instructional materials on grade nine learners’ performance in chemistry. It is a quasi-experimental study that employed pre- and post- test to investigate the impacts of improvised instructional materials on learners’ chemistry performance. A sample of 450 learners randomly selected was used in this study. Thus, a researcher formed two groups, control group made of 255 learners taught with traditional lecture teaching method and an experimental group made of 255 learners that was taught using improvised instructional materials. Learners in both groups were given a survey questionnaire to fill about their views in relation to the use improvised materials. In addition, the researcher gave a pre-test and a post-test to learners in both groups before and after intervention. The results from survey questionnaire showed that learners learned actively and performed better when they learned through improvised instructional materials. The pre-test results [t (248) = .0992; P>0.5] showed that there was no difference in learners’ performance. However, post-test results [t (248) = .000; P<0.5], showed a significant difference in learners’ performance in favor of those taught with improvised instructional materials. It is, therefore, recommended that chemistry teachers develop and use regularly improvised instructional materials to broaden learners’ knowledge and to improve chemistry learners' performance through hands-on activities.

This study intended to explore the contribution of Task-Based Learning (TBL) to raising students' attitudes toward learning chemistry. The study employed a quasi-experimental research design with 369 secondary school grade-2 students in Rwanda. The study randomly assigned students to two groups of differentiated instruction. Thus, the experimental group was exposed to the TBL method, while a control group was taught the teacher-centered method. An internationally standardized Chemistry attitude questionnaire of 0.831 Cronbach alpha reliability coefficient was used before and after teaching and learning activity. The Kruskal Wallis test was computed in SPSS 23.0 to measure the effect of TBLin raising positive attitudes among students in the experimental group compared to the control group. The attitude gain was measured from pre-test to post-test in attitude variables. This study showed a statistically significant difference between the control group and the experimental group (ꭓ2 = 4.118, df = 1, p < .05). Furthermore, the students perceived chemistry's importance more than the other three variables (difficulty, interest, and usefulness of chemistry). Results also showed that gender affected students' perceptions of learning chemistry. Females students developed more positive attitudes than male students. However, school location statistically affecting students' attitudes towards chemistry. The study result implies that TBL method helped to increase students' attitudes toward chemistry. Recommendations were given to implement TBL methods in the chemistry classroom.

This study intended to measure the effect of Task-Based Learning (TBL) on lower secondary school students’ understanding of chemical reactions. The study employed a quasi-experimental pre and post-test research design with eight intact classes of 369 students purposively selected from eight schools in two districts in Rwanda. The experimental group of four schools was exposed to the TBL method, while a control group of the other four schools was exposed to the conventional teaching method (teacher-centered). A chemistry test of a Pearson product-moment reliability coefficient of .643 was developed and used in both groups. The results of repeated-measures ANOVA revealed a significant effect of treatment on students’ understanding of chemical reactions (p < .001) with a medium effect size (d = 0.357) in favor of the experimental group. Gender and school location variables were also analyzed. It was found that the interaction effect of experimental and gender was not significant (p > .05, d = 0.010). However, the effect was significant with the school location (p < .05, d = 0.026) in favor of students studying in rural schools. The results imply that TBL method improves students’ understanding of chemical reactions. Recommendations were given to educational stakeholders to train teachers in this method and teachers to use it in chemistry teaching. Keywords: chemistry education, chemical reactions, Rwandan lower secondary schools, students’ understanding, task-based learning

Smartphones and computer-based technology have revolutionized different development sectors including education. The current review describes the existing literature on Web-Based Learning (WBL) as a novel methodology applied in teaching and learning, and its potential effectiveness in teaching and learning chemistry. Further, the study intends to reflect on how the WBL could be applied in the Rwandan context of teaching and learning chemistry as the country adopted the competency-based curriculum (CBC) in 2015. This review is a narrative overview in which much of the existing literature such as books, articles, and other online literatures related to the study were reviewed. The literature was obtained from different electronic databases including Scopus, ERIC, ISI web of knowledge, academia, web of science, digital library, and google scholar.

The past decade has seen a significant shift from teacher-centered pedagogy to a learner-centered approach in chemistry education research. Game-based learning has emerged as one of the most beneficial instructional approaches because it emphasizes "hands-on" and "minds-on" activities in chemistry classrooms. However, there has been a scarcity of review studies in chemistry education research that have attempted to document different educational games implemented and how such games have contributed to enhancing students' motivation and understanding of chemistry concepts. A total of 57 articles were reviewed to identify educational games implemented in chemistry classrooms from 2010 to 2021 to address this gap. All the reviewed articles were downloaded from the Google Scholar search engine and have all been indexed by Scopus. A systematic analysis was adopted to identify the purposes, educational game designs and implementation, and the chemistry content areas of focus for all the reviewed studies. Results show that educational games enhance students' conceptual understanding of chemistry and increase their motivation to learn and have fun while making sense of the learned content.

21st century teaching and learning emphasize the full engagement of students for improving their critical thinking and cooperation and the construction of the knowledge that demonstrates deep understanding. However, significant studies reported chemistry as a challenging subject caused of abstract concepts, phenomena and ways used in teaching and assessment. In this regard, rubrics were developed as guidelines to judge and score students’ activities and see their achievements. As an assessment tool, a rubric is crucial in the twenty-first century for self-directed learning and individual students’ assessment of the intended learning outcomes. Some teachers and researchers acknowledge the role of rubrics in teaching and learning chemistry. However, the application of rubrics is quite unconsidered. Thus, the present systematic review stresses the 21st-century overview of rubric materials and their progress in application in chemistry teaching and students’ learning enhancement. In cooperation, chemistry teachers and students are encouraged to successfully use rubrics for teaching, learning and as well as in the assessment process as a supporting learning tool. Rubrics have great importance in helping assessors be consistent in scoring students’ activities and availing assessment anticipations to students. Thus, integrating rubrics in teaching and learning chemistry improves students understanding of this subject.

This study aims at assessing the classroom practices of Rwandan chemistry teachers in secondary schools, the second grade (S2), age range between 14 to 16 years old. The classroom observation conducted using the Classroom Observation Protocol for Undergraduate STEM (COPUS). In general, the best practice of group work or collaborative learning and students' engagement was observed. The analysis of the COPUS data reveals that active learning in chemistry classes is dominating, 54% against 42% of passive learning; found high, statistically significant over passive learning at p < .01 (tCritical = 1.89, df = 7, p = .003). The active students' practice is taking 82% of a 2-min time interval across 30 lessons observed, as one class period has 40 min to make 20 intervals of 2 min. Teachers are engaging their students in collaborative learning by assigning them various tasks in groups. These results established the current instructional practices in chemistry classes to draw conclusions and recommendations.

Science education is facing a challenge of students who are losing interest in learning science subjects including chemistry. This research provides a review of literature that emphasizes on the factors affecting secondary school students’ attitudes toward chemistry. Thirty-six studies were selected in Google scholar and ERIC database in the time frame from 1977 to 2019. Gender, instructional methods, and grade level were found to be the most common factors positively affecting students’ attitudes toward chemistry. However, students’ interest, classroom environment, the relevance of curriculum, teachers’ behavior, perceived difficulty and self-directed effort in the science subjects were also studied to check if there is any relation to the attitude of students while learning chemistry. The findings indicated that these factors have to be controlled to enrich positive attitudes toward chemistry among secondary students and to improve their performance in chemistry.

Improved teaching methods facilitate the ease of acquisition of knowledge and lead to better achievement. The present study investigates the instructional methods most commonly used in teaching chemistry in lower secondary schools in Rwanda. SPSS 23.0 was used to analyze data from a survey conducted on 51 lower secondary chemistry teachers. The survey has satisfactory and acceptable reliability (Cronbach alpha=0.913 for 57 items on average). The results revealed that teachers prefer active learning methods though they still use traditional teaching methods. Comparison of teachers’ responses in terms of experience showed no statistically significant difference with p= 0.064. The study also found that some teachers have misconceptions in differentiating instructional approaches, methods, and techniques or strategies. Therefore, it is recommended that educational stakeholders should plan pieces of training to teachers about different instructional methods and techniques to use in chemistry teaching for effective learning outcomes.

Some learners perceive chemistry as a complex subject to learn, saying teaching is boring and not enjoyable. There is a need for making the learning experience more enjoyable to make chemistry easy to understand. This study aims to assess the effect of activity-based teaching techniques compared to the conventional technique on the performance of students in chemistry. The study was quasi-experimental-based research using both pre and post-test, achievement tests. The sample comprised 166 students, as a total number of students in four classes, from a population of 1610 students of the second grade of secondary classes (S2) studying the Properties of Organic Compounds and Uses of Alkanes. Pre-test was conducted, and its data was collected before the intervention, and the post-test was conducted and data was collected after the intervention. Both the descriptive and inferential statistical tests were applied in the analysis. Students’ performance gain in chemistry was higher in the treatment classes as the mean value was 6.81 and the standard deviation was 1.66 (M = 6.81, SD = 1.66) than that of the comparison classes (M = 6.35, SD = 1.78). However, difference was not significant, t(164) = -1.73, p = .085. Teachers should be supported in designing physical pedagogical activities for improving learning outcomes in chemistry.

This study aims at determining the effect of the pedagogical technique most frequently used while implementing the competency-based curriculum (CBC) in teaching chemistry in senior two (S2) classes (age range 14-16) and the teachers' alignment with the scheme of work. It was conducted in 10 selected Rwandan secondary schools using a teacher survey, teacher interviews and the Classroom Observation Protocol for Undergraduate STEM (COPUS) in the period from 27 May to 8 July 2019. The result of the analysis reveals that teaching chemistry using group work-related techniques that engage more learners does not have any relationship to teachers moving slowly compared to the scheme of work of S2 chemistry. Therefore, this study recommends more support for teachers to use active learning techniques in teaching chemistry in S2 for the effective implementation of the CBC.

The chemistry of aroylhydrazines has been attracting attention mainly due to the residual functional group, –CONH–NH2, which has important effects on hydrophilicity and has the potential to provide special interaction sites for targeting molecules.

The study aims to reinforce the effective teaching of chemistry in secondary schools through the support of the school leadership in the implementation of the competence-based curriculum (CBC). Interviews were organised and conducted with five headteachers and five deputy headteachers from ten selected schools. The results confirmed that the support provided by the school leadership in teaching chemistry was dominated by 30% of respondents at visiting teachers in classes, provision of some basic teaching materials and encouraging teachers to work in the chemistry department for mutual support and professional growth. However, in some schools, there is a need for prioritising continuous professional development (CPD) opportunities, feedback meetings and analysing school data for decision making. Therefore, this study recommends more efforts in CPDs, avail enough teaching aids and hold the pedagogical review and learning meetings lead by headteachers; analyse and use the school data for continuous improvement and build the school on tangible evidence in positive learning outcomes. Plus more support in engaging learners doing chemistry rather than just giving them chemistry books. Transformational leadership is needed, where all stakeholders share the same vision and mission of the school.

The distribution and concentrations of 6 indicator polychlorinated biphenyl (PCB) congeners, nos. 23,52,101, 138, 153 and 130, were determined in surface sediments from the North End Lake in Port Elizabeth, South Africa. Forty-two surficial sediment samples were collected from different locations covering the region that receives the majority of the industrial waste, urban effluents and runoff and thus expected to be contaminated with different degrees of contamination. Tire analysis was achieved by gas chromatography-mass spectrometry (GG/MS) using the internal standard method. The total PCB concentrations in the samples ranged from 1.60 to 3.06 ng.g(-1) dry weight (dw). The concentrations of congener profiles showed significant differences. Generally, the highest PCB concentrations were associated with high organic matter contents and small grain size. Tire highly chlorinated PCBs dominated with regards to the levels in sediments. PCB 138 was the major contributor to the total PCBs and was detected at 100% of sites. This study provided a snapshot of the PCB contamination status in the North End Lake sediments, and allowed for a comparison between the investigated system and other systems worldwide.

This study investigated the effect of freshwater as a point source of PCBs contributing to a marine outfall region. Inflowing and outflowing water from the North End Lake, Port Elizabeth, was collected to determine the contamination levels of polychlorinated biphenyls (PCBs). Mussels at the outflow to the sea were also sampled. The samples were analysed by an internal standard method for 6 indicator PCB congeners using gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring (SIM) mode. The total PCB concentrations in the water (dissolved plus particulate phases) ranged from 0.180 to 0.355 ng.L-1 and from 20.84 to 31.34 ng.g(-1) wet weight (ww) in mussels. Lighter PCB congeners exhibited highest concentrations in the water samples while heavier PCBs were dominant in mussels. PCB-52 was the most abundant in the water samples while PCB-153 was abundant in mussels. To protect human health from the possible effects of eating fish and shellfish contaminated with PCBs, the Environmental Protection Agency regulates that the level of PCBs in water be no greater than 0.17 ng.L-1 of water. The levels of PCBs in water from the North End Lake were found to be high (0.180-0.355 ng.L-1) compared to the levels recommended by EPA.

Sediment and Mytilus galloprovincialis samples collected from the Port Elizabeth Harbour were analysed for six indicator PCB congeners to assess their contamination status. The concentrations of total PCBs in sediments and M. galloprovincialis ranged from 0.56 to 2.35 ng/g dry weight and 14.48 to 21.37 ng/g wet weight, respectively. Congeners 138 and 153 were dominant and accounted for an average of 29% and 24% of total PCBs in M. galloprovincialis; 32% and 30% in sediments, respectively. Sediments are home to a wide variety of aquatic life. None of the sediments analysed exceeded the PCB limits recommended the Canadian interim sediment quality guideline and the South African recommended sediment guidelines (21.6 ng/g). Both humans and aquatic life are sensitive to the toxic effects of PCBs.

The concentrations and distribution of 6 PCB indicator congeners (IUPAC nos. 28, 52, 101, 138, 153, and 180) were measured in 236 organ samples of fish (Cyprinus carpio and Oreochromis mossambicus) from the North End Lake in Port Elizabeth, South Africa. Polychlorinated biphenyls (PCBs) were extracted from the fish muscles, gills, gonads and livers using USEPA method 8082, followed by a clean-up using concentrated sulphuric acid and florisil column chromatography. Analysis was achieved by gas chromatography-mass spectrometry (GC/MS) using the internal standard method. The concentrations of total PCBs in the liver, gonads, gills and muscle were 95.69, 57.49, 44.63, 34.14 ng.g(-1) lipid weight (lw) in C. carpio and 119.73, 59.21, 49.78, 34.63 ng.g(-1) (lw) in O. mossambicus, respectively. These values were relatively low compared to those reported in the literature. PCB levels were predictably highest in the lipid-rich livers. Individual congeners were not distributed homogeneously within the investigated organs. PCBs 153 and 138 were present at higher concentrations than other PCB congeners for both species. PCB contaminants in fish act as indicators of pollution in aquatic ecosystems and are a potential threat to human health when consumed.