Although there is an invaluable growth of science and technology across the world, many young people appear to lose interest in Mathematics and science-related subjects due to poor academic achievement caused by different factors. The factors affecting students' achievement in science subjects among sub-Saharan Africa countries,including Rwanda, have been an issue for stakeholders on investigating how to improve the teaching and learning of science in basic education. In this study, a purposive cluster sampling of 261 participants, including 210 students, 23 teachers, seven head teachers, seven Sector Education Inspectors (SEIs), and 14 parents were used. Data were collected through a questionnaire addressed to learners; analyzed using SPSS via descriptive statistics. An interview was conducted with students' representatives, teachers, head teachers,Sector Education Inspectors, and focus group discussion with 14 parents which was analyzed using content analysis. The analysis indicated that key factors of low performance in science subjects include the level of teachers' education; family's economic background; availability of teaching and learning materials; distance covered by learners from home to school; learner's prior knowledge; and level of parents'education and absenteeism of learners. Thus, the above seem to affect the academic achievement of students in the advanced level of Twelve-Year Basic Education in Rwanda. Views about how to improve learning achievements in science such as equipping the laboratories, constructing more 12YBE schools in various areas to curb the problem of long distances covered by learners to and from school, training teachers on innovative teaching methods were suggested. The results informed that in-service teachers' training and parental involvement should be encouraged to track and sustain learners’ learning.

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A hydrothermal synthesis route was used to synthesize iron(III) phosphate hydroxide hydrate-carbon nanotube composites. Carbon nanotubes (CNT) were mixed in solution with Fe(PO)(OH)(HO) (FPHH) precursors for one-pot hydrothermal reaction leading to the FPHH/CNT composite. This produces a highly electronic conductive material to be used as a cathode material for Li-ion battery. The galvanostatic cycling analysis shows that the material delivers a specific capacity of 160 mAh g at 0.2 C (0.2 Li per fu in 1 h), slightly decreasing with increasing current density. A high charge-discharge cyclability is observed, showing that a capacity of 120 mAh g at 1 C is maintained after 500 cycles. This may be attributed to the microspherical morphology of the particles and electronic percolation due to CNT but also to the unusual insertion mechanism resulting from the peculiar structure of FPHH formed by chains of partially occupied FeO octahedra connected by PO tetrahedra. The mechanism of the first discharge-charge cycle was investigated by combining operando X-ray diffraction and Fe Mössbauer spectroscopy. FPHH undergoes a monophasic reaction with up to 10% volume changes based on the Fe/Fe redox process. However, the variations of the FPHH lattice parameters and the Fe quadrupole splitting distributions during the Li insertion-deinsertion process show a two-step behavior. We propose that such mechanism could be due to the existence of different types of vacant sites in FPHH, including vacant "octahedral" sites (Fe vacancies) that improve diffusion of Li by connecting the one-dimensional channels.

A B S T R A C TThe sodium-manganese-iron phosphate Na 2 Mn 1.5 Fe 1.5 (PO 4 ) 3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na + and presence of vacancies in A(2)', Na + and small amounts of Mn 2+ in A(1), Mn 2+ in M(1), 0.5 Mn 2+ and Fe cations (Mn 2+ ,Fe 2+ and Fe 3+ ) in M(2), leading to the structural formula Na 2 Mn(Mn 0.5 Fe 1.5 ) (PO 4 ) 3 . The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 h at 220°C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220°C for 6 h. When the reaction time was increased from 6 to 12, 24 and 48 h, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mA h g −1 for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99% during 50 cycles.

Chemistry subject continues to be considered as difficult to teach and learn. This leads to students’ low academic achievement, retention, and negative attitude towards the subject. Organic chemistry as one of the concepts on which technological advancement is constructed sometimes appears to be enormously complex to students. There are some persisting misconceptions about it although different innovative instructional strategies have been applied and this area is of main concern as the learning of students can be extremely hindered in case their misconceptions are not minimized and/or corrected. The review then is to equip educators with knowledge about organic chemistry concept and source of students ‘misconceptions; the misconceptions of students about organic chemistry; the ways of diagnosing students’ misconceptions and remedies of those misconceptions; some learning theories for the effective organic chemistry instruction and classroom implications. The paper is also useful to know more about the minimization of students’ misconceptions and leading them to the great academic achievement and interest towards the subject by employing cooperative learning models; thus, many other different innovative teaching strategies are recommended to apply in organic chemistry instruction

Secondary school students continue to consider chemistry as difficult to learn and develop a negative attitude towards it. This leads to low achievement in the subject and reduces their interest. Studies on students' achievement in chemistry have been conducted and different instructional strategies of teaching and learning have been provided. Nonetheless, there are persisting misconceptions and factors that hinder the achievement of students, even after the implementation of suggested strategies. By applying innovative teaching approaches as remedial to teaching and learning barriers, students' achievement may be improved; and the retention of the learned material may be enhanced. In this study, we conducted a literature search to collect any related literature. Sixty-one studies were obtained; some of them were not related to our investigation; and those which did not answer the research question were excluded, we remained with 13 studies. The selection of studies was based on year of publication, and language. These studies were published in English and between 2011 and 2021. Consequently, this review highlights the influence of teaching methods on students' achievements, updating teachers on the factors affecting students' achievements in Chemistry, misconceptions in chemistry instruction, and ways for remedying those misconceptions, as well as methods for improving students’ academic achievements.

<p style="text-align: justify;">The cooperative learning (CL) is an advanced instructional approach that uses different motivational procedures to make instruction significant and learners more responsible. This study aimed to investigate the effects of cooperative learning on students' achievement in chemistry among the advanced level in 12-year basic education schools; it engaged a quasi-experimental design with one treatment group and a comparison group (control); the first applied cooperative learning in teaching organic chemistry while in the control group, organic chemistry was taught by the conventional teaching methods (CTM). A sample of 257 students participated in the study. The data collected used an organic Chemistry Achievement Test, and its data were analyzed using SPSS version 23.0 and MS Excel 2016. The ANCOVA results showed that learners taught using cooperative learning achieved better than their counterparts in the control group (F=78.07, df=1, 256, p<.001) with the learning gains of 16.0% in traditional methods and 53.6% of cooperative learning approach, respectively. However, there was no statistically significant difference in gender of students. It is recommended that chemistry teachers be trained on cooperative learning and encouraged to apply it in their teaching methods to enhance students' academic achievement.</p>

The study complements previous research on a case study of chemistry lesson plans design and teaching. It has been found that chemistry education in The Gambia has been challenged by ineffective lesson plans design and teaching, and laboratory resources. The consequences have been unsatisfactory learning outcomes. However, what could lead to unsatisfactory learning outcomes in chemistry if basic stoichiometry is considered challenging? This has led the present study to develop a survey research method to assess students' misconceptions on basic stoichiometry. Through a systematic random sampling technique, 285-grade eleventh students were selected. The topics covered in the study included interpreting the pH of common substances, balancing basic stoichiometric equations, and inferences of experimental results. Students’ responses to misconception survey questions were reviewed and analysed. The results indicated that students could be taught some basic principles of stoichiometry. Students who were challenged to correct inferences from experimental results need to develop their knowledge better. Accordingly, the study concluded that chemistry education can indicate the success of introducing basic stoichiometry, including referencing to the lower grades, rather than secondary grades. Nevertheless, what this study could recommend was to examine the possible source and cause of such misconceptions concerning basic stoichiometry reactions and balancing. Keywords: basic stoichiometry, chemical reactions, pH values interpretation, students’ misconceptions