How CLUE-d up are you?

Among the most important skills a chemist has is the ability to predict and explain phenomena based on chemical structures. Monitoring how these skills develop can help in identifying which teaching strategies lead to the most effective learning. In a recent study,¹ Sonia Underwood and colleagues describe the use of such monitoring to judge the effectiveness of an alternative general chemistry curriculum against a more traditional approach.

Several hundred students in two cohorts from a research university in the southeastern US, had their understanding probed using the Implicit Information from Lewis Structures Instrument (IILSI). The IILSI comprises a single multiple choice question: ‘what information could you determine from a Lewis structure and any other chemistry knowledge you may have?’ Students can select from 16 pieces of information, which may or may not be determinable from a Lewis structure, relating to explicit (eg the elements present) and implicit (eg acid–base properties, relative boiling point) information.

Previous work using the IILSI showed that even after two years of chemistry, many students did not recognise that they could predict properties from molecular structures. In this study, students’ developing understanding was monitored over time by administering the IILSI at five points over two years, during which they took four courses in general chemistry and organic chemistry. The data is presented in the form of competency curves that illustrate the proportion of students who select a given IILSI response item at different time points, visualising the development of the cohort’s competence over time.

This method was used to compare the progress of students studying traditionally delivered courses against those studying a new curriculum known as ‘Chemistry, Life, the Universe and Everything’ (CLUE). The latter is built around the interconnectedness of core chemical ideas, which are developed over time to encourage coherent understanding. Competency curves illustrating the progress of students studying each curriculum beautifully illustrate that the CLUE students connect structure and properties much earlier than the students of the traditional curriculum. These differences persist throughout the study, ie students of the traditional curriculum fall behind early on and never catch up. The authors suggest that instructors wishing to emulate the success of the CLUE approach should reinforce structure–property relationships regularly, and use assessments that require the construction of explanations in preference to multiple choice tests.