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The aims of this study were to evaluate reliability and validity of the Students' Perception of Assessment Questionnaire (SPAQ), to evaluate students' perception on assessment, and to evaluate gender-based, grade-based, and ethnicity-based differences in students' perceptions. The validity and reliability coefficients revealed that the SPAQ was suitable for assessing students' perceptions on five assessment dimensions. The average scale-item mean values for all the scales were less than 3.0, which indicates a need to address these dimensions of assessment at classroom level. The mean value for Student Consultation scale was 1.96 out of 4, indicating a need for special attention in this area. The perceptions of students grouped on the basis of gender and of grade level groups were comparable, but on the basis of ethnic groups were statistically significantly different. Assuming these differences to be real, does it mean that teaching approaches will need to be addressed? Future research in this area is warranted.

As an important subject in the curriculum, many students find chemistry concepts difficult to learn and understand. Chemical bonding especially is important in understanding the compositions of chemical compounds and related concepts and research has shown that students struggle with this concept. In this theoretical paper based on analysis of relevant science education research, textbooks, and our classroom observations and teaching experiences, the authors argue that the difficulty in learning chemical bonding concepts is associated with the sequence (ionic, covalent and polar covalent bonding) in which students are taught because this sequence receives little support from constructivist theories of learning. Consequently, the paper proposes a sequence to teach chemical bonding (covalent, polar covalent and ionic bonding) for effective and sustainable learning. In this sequence, the concepts are developed with minimum reorganisation of previously learned information, using a format which is claimed to be easy for students to learn. For teaching these concepts, the use of electronegativity and the overlap of atomic orbitals for all types of bonding have also been stressed. The proposed sequence and emphasis on electronegativity and atomic orbital overlap meets the criteria for teaching and learning of concepts based on the psychology of learning including the theory of constructivism necessitating the construction of new knowledge using related prior knowledge. It also provides a better linkage between the bonding concepts learned at secondary and tertiary levels. Considering these proposed advantages for teaching, this sequence is recommended for further research into effective and sustainable teaching.

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