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Students are generally known to memorise and regurgitate chemical equations without sufficient understanding of the changes that occur at the particulate level. In addition, they often fail to recognise the significance of the symbols and formulas that are used to represent chemical reactions. This article describes an evaluation of the ability of 65 Grade 9 students (15–16 years old) from a Singapore secondary school to describe and explain seven types of chemical reactions using macroscopic, submicroscopic and symbolic representations. The study was conducted over nine months using a supplementary teaching program with particular emphasis on the use of multiple levels of representation to describe and explain chemical reactions. Students’ proficiency in the use of multiple levels of representation was assessed at the end of the course using a two-tier multiple-choice diagnostic instrument that was …