Choose chemical representations carefully

The use of different representations and visualisation approaches to explain chemical concepts plays a key role in supporting chemistry students’ learning. Teachers’ decisions about which representations to use, and how to use them, are critical and depend on their own experiences and mental models of concepts. However, poor combinations of representations impede learning.

João Ferreira and Gwendolyn Lawrie investigated the use of combinations of representations from a series of lecture slides used for introductory chemistry at an Australian university. The representations – which included illustrations, internet images, diagrams, drawings and photographs – from a set of over 900 lecture slides created and revised over about 10 years and by 20 educators were characterised in accordance with the different frameworks. The study focused on the use of multiple representations that supported deep learning, drawing on work to identify examples in which knowledge could be applied by students to translate or construct references between known and unknown representations. Although active learning approaches had been introduced to the course over the years, much of the content was still presented as Powerpoint slides to large student cohorts.

Unsurprisingly, symbolic representations were the most common, and some lecture slides contained as many as six representations. Topics were typically introduced by using symbolism that students were probably familiar with to reinforce and expand their representational fluenc. There were fewer examples of macroscopic and sub-microscopic representations, but there were links to simulations (sub-microscopic) on some slides and in-class demonstrations (macroscopic) were used on numerous occasions.

In addition, the authors point out the importance of educators’ gestures and real-time drawing to bring representations to life. These dynamic types of representation could form the basis of an interesting future study, although how you would go about categorising them would pose a challenge. However, the value of this study has already been demonstrated through its use in a review of the teaching materials examined, which resulted in improved strategies for combining representations and reducing cognitive load through the removal of extraneous examples.