Understanding Acid-Base Concepts: Evaluating the Efficacy of a Senior High School Student-Centred Instructional Program in Indonesia

This study was a mixed quantitative–qualitative research to evaluate the efficacy of a designed student-centred instructional (DSCI) program for teaching about acids and bases. The teaching innovation was designed based on constructivist, hands-on inquiry and context-based approaches and implemented in seven 45-min lessons with a class of 36 grade 11 students (experimental group) from a public senior high school in Indonesia. Another class of 38 students (comparison group) from the same school was instructed using a traditional teacher-centred approach. Data were obtained using a (1) 12-item achievement test on acids and bases that was administered to both groups as a pretest and a posttest, (2) self-evaluation 13-item questionnaire on students’ perceptions of their competence and confidence in carrying out the inquiry activities that was administered to the experimental group and (3) 3-item open-ended questionnaire on students’ perceptions of the instructional process using the DSCI that was administered to the experimental group.The results of the study showed that the teaching innovation was effective in improving students’ understanding of acid–base concepts with significant difference between the two groups on the posttest mean scores. Moreover, the effectiveness of the innovation was supported by an increase in students’ interest in learning science as indicated by their (1) positive perceptions of their engagement and competence in doing inquiry activities, (2) positive perceptions of the learning environment and (3) positive outcome expectations. The findings have implications for chemistry teaching in any institution with similar achieving students as well as for the professional development of teachers

Using metacognitive strategies in teaching to facilitate understanding of light concepts among year 9 students

Background: Enhancing students’ metacognitive abilities will help to facilitate their understanding of science concepts. Purpose: The study was designed to conduct and evaluate the effectiveness of a repertoire of interventions aimed at enhancing secondary school students’ metacognitive capabilities and their achievements in science. Sample: A class of 35 Year 9 students participated in the study. Design and methods: The study involved a pre-post design, conducted by the first author as part of the regular designated science programme in a class taught by him. In order to enhance the students’ metacognitive capabilities, the first author employed clearly stated focused outcomes, engaging them in collaborative group work, reading scientific texts and using concept mapping techniques during classroom instruction. The data to evaluate the effectiveness of the metacognitive interventions were obtained from pre- and post-test results of two metacognitive questionnaires, the Metacognitive Support Questionnaire (MSpQ) and the Metacognitive Strategies Questionnaire (MStQ), and data from interviews. In addition, pre-test and post-test scores were used from a two-tier multiple-choice test on Light.Results: The results showed gains in the MSpQ but not in the MStQ. However, the qualitative data from interviews suggested high metacognitive capabilities amongst the high- and average-achieving students at the end of the study. Students’ gains were also evident from the test scores in the Light test. Conclusion: Although the quantitative data obtained from the Metacognitive Strategies Questionnaire did not show significant gains in the students’ metacognitive strategies, the qualitative data from interviews suggested positive perceptions of students’ metacognitive strategies amongst the high- and average-achieving students. Data from the Metacognitive Support Questionnaire showed that there were significant gains in the students’ perceptions of their metacognitive support implying that the majority of the students perceived that their learning environment was oriented towards the development of their metacognitive capabilities. The effect of the metacognitive interventions on students’ achievement in the Light test resulted in students displaying the correct declarative knowledge, but quite often they lacked the procedural knowledge by failing to explain their answers correctly

Consequences of a telomerase-related fitness defect and chromosome substitution technology in yeast synIX strains

We describe the complete synthesis, assembly, debugging, and characterization of a synthetic 404,963 bp chromosome, synIX (synthetic chromosome IX). Combined chromosome construction methods were used to synthesize and integrate its left arm (synIXL) into a strain containing previously described synIXR. We identified and resolved a bug affecting expression of EST3, a crucial gene for telomerase function, producing a synIX strain with near wild-type fitness. To facilitate future synthetic chromosome consolidation and increase flexibility of chromosome transfer between distinct strains, we combined chromoduction, a method to transfer a whole chromosome between two strains, with conditional centromere destabilization to substitute a chromosome of interest for its native counterpart. Both steps of this chromosome substitution method were efficient. We observed that wild-type II tended to co-transfer with synIX and was co-destabilized with wild-type IX, suggesting a potential gene dosage compensation relationship between these chromosomes. </p

Effects of a Mathematics Cognitive Acceleration Program on Student Achievement and Motivation

This paper presents the effects of a cognitive acceleration program in mathematics classes on Tongan students’ achievements, motivation and self-regulation. Cognitive Acceleration in Mathematics Education (CAME) is a program developed at King’s College and implemented worldwide with the aim of improving students’ thinking skills, mathematics performance and attitudes. The first author adapted the program materials to Tongan educational context and provided support to participating teachers for 8 months. This study employed a quasi-experimental design with 219 Year 8 students as the experimental group and 119 Year 8 students as the comparison group. There were a significant differences in the mean scores between the pre-test and post-test of the three instruments that were employed in the study, indicating that learning mathematics under the CAME program had a positive effect on levels of students’ self-regulation, motivation and mathematics achievement. Students also reported changes to the ways they learn mathematics

High School Students' Proficiency and Confidence Levels in Displaying Their Understanding of Basic Electrolysis Concepts

This study was conducted with 330 Form 4 (grade 10) students (aged 15 – 16 years) who were involved in a course of instruction on electrolysis concepts. The main purposes of this study were (1) to assess high school chemistry students’ understanding of 19 major principles of electrolysis using a recently developed 2-tier multiple-choice diagnostic instrument, the Electrolysis Diagnostic Instrument (EDI), and (2) to assess students’ confidence levels in displaying their knowledge and understanding of these electrolysis concepts. Analysis of students’ responses to the EDI showed that they displayed very limited understanding of the electrolytic processes involving molten compounds and aqueous solutions of compounds, with a mean score of 6.82 (out of a possible maximum of 17). Students were found to possess content knowledge about several electrolysis processes but did not provide suitable explanations for the changes that had occurred, with less than 45 % of students displaying scientifically acceptable understandings about electrolysis. In addition, students displayed limited confidence about making the correct selections for the items; yet, in 16 of the 17 items, the percentage of students who were confident that they had selected the correct answer to an item was higher than the actual percentage of students who correctly answered the corresponding item. The findings suggest several implications for classroom instruction on the electrolysis topic that need to be addressed in order to facilitate better understanding by students of electrolysis concepts

Project management between will and representation

This article challenges some deep-rooted assumptions of project management. Inspired by the work of the German philosopher, Arthur Schopenhauer, it calls for looking at projects through two complementary lenses: one that accounts for cognitive and representational aspects and one that accounts for material and volitional aspects. Understanding the many ways in which these aspects transpire and interact in projects sheds new light on project organizations, as imperfect and fragile representations that chase a shifting nexus of intractable human, social, technical, and material processes. This, in turn, can bring about a new grasp of notions such as value,\ud knowledge, complexity, and risk

Repair at Single Targeted DNA Double-Strand Breaks in Pluripotent and Differentiated Human Cells

Differences in ex vivo cell culture conditions can drastically affect stem cell physiology. We sought to establish an assay for measuring the effects of chemical, environmental, and genetic manipulations on the precision of repair at a single DNA double-strand break (DSB) in pluripotent and somatic human cells. DSBs in mammalian cells are primarily repaired by either homologous recombination (HR) or nonhomologous end-joining (NHEJ). For the most part, previous studies of DSB repair in human cells have utilized nonspecific clastogens like ionizing radiation, which are highly nonphysiologic, or assayed repair at randomly integrated reporters. Measuring repair after random integration is potentially confounded by locus-specific effects on the efficiency and precision of repair. We show that the frequency of HR at a single DSB differs up to 20-fold between otherwise isogenic human embryonic stem cells (hESCs) based on the site of the DSB within the genome. To overcome locus-specific effects on DSB repair, we used zinc finger nucleases to efficiently target a DSB repair reporter to a safe-harbor locus in hESCs and a panel of somatic human cell lines. We demonstrate that repair at a targeted DSB is highly precise in hESCs, compared to either the somatic human cells or murine embryonic stem cells. Differentiation of hESCs harboring the targeted reporter into astrocytes reduces both the efficiency and precision of repair. Thus, the phenotype of repair at a single DSB can differ based on either the site of damage within the genome or the stage of cellular differentiation. Our approach to single DSB analysis has broad utility for defining the effects of genetic and environmental modifications on repair precision in pluripotent cells and their differentiated progeny

Students' dilemmas in reaction stoichiometry problem solving: deducing the limiting reagent in chemical reactions

A qualitative case study was conducted to investigate the understanding of the limiting reagent concept and the strategies used by five Year 11 students when solving four reaction stoichiometry problems. Students’ written problem-solving strategies were studied using the think-aloud protocol during problem-solving, and retrospective verbalisations after each activity. Contrary to several findings reported in the research literature, the two high-achieving students in the study tended to rely on the use of a memorised formula to deduce the limiting reagent, by comparing the actual mole ratio of the reactants with the stoichiometric mole ratio. The other three average-achieving students, however, generally deduced the limiting reagent from first principles, using the stoichiometry of the balanced chemical equation. Overall, the students displayed limited confidence during problem-solving to determine the limiting reagent and to perform related computations

Evaluation of an Intervention Instructional Program to Facilitate Understanding of Basic Particle Concepts Among Students Enrolled in Several Levels of Study

The efficacy of an intervention instructional program was evaluated to facilitate understanding of particle theory concepts among students (N = 190) using a diagnostic instrument consisting of eleven two-tier multiple-choice items in a pre-test – post-test design. The students involved were high school students, undergraduates and postgraduates from six educational levels. The eleven items evaluated understanding in three key conceptual categories: (1) intermolecular spacing in matter, (2) the influence of intermolecular forces on changes of state and (3) diffusion in liquids and gases. The intervention program proved effective in improving students' overall understanding of particle theory concepts, with statistically significant improvement in overall scores among students in five of the six groups. However, only 25-46% of the students displayed consistent understanding of the concepts in the three conceptual categories