Triangulation to tame the Triplet

Johnstone’s Triangle, commonly known as the ‘Triplet’, refers to the three different levels of representation that operate in chemistry. In this model, students should be able to describe changes in macroscopic properties (colour/enthalpy changes), explain such changes at molecular or atomic levels, and use symbolic representations to communicate these changes.

Triangulation is the conscious mental process of trying to relate all three types of representation to develop understanding. The aim is to connect what a student knows about chemical phenomena to changes, reactions, etc using the three types of representation.

The study involved one teacher at a school in Canada who had over ten years of experience in the classroom. Prior to the study, the teacher’s practice was described as traditional, with didactic instruction, demonstrations and laboratory work accompanying frequent worksheets and lab reports. Metacognitive demands were described as ‘modest’. In collaboration with the researcher, the teacher devised a new strategy to support students’ understanding and use of triangulation in chemistry lessons.

They developed a worksheet to direct students’ thought processes to address each of the representations and the relationships between them when considering a chemical phenomenon or concept. To support their thinking about representations, students were prompted by questions relating to atoms, molecules, and electrons in matter, and how ‘events’ can be visualised. There were also questions about how to communicate about events at the invisible sub-microscopic level.

At appropriate moments the teacher would say ‘everyone triangulate’, prompting students to complete the worksheet related to the current topic. They were then asked to move to the board to share diagrams and explanations with the class, initiating discussions about the relationships between the representations, which provided opportunities for formative assessment.

Of 13 students interviewed (from a class of 27), nine thought this approach was beneficial, with comments indicating these students had developed their skills of metacognitive reflection. One quote suggested ‘The triangulation process is probably the most useful thing I’ve learned all year.’ The remaining four students felt triangulation was not beneficial to their learning, although there was still evidence of enhanced reflection in their discussions during the interview.

Although the study doesn’t discuss the impact on attainment, the approach prompted students to reflect. There is a strong suggestion that direct instruction relating to metacognition and learning strategies was critical in this outcome.

As indicated in the study, some students are reluctant to adopt new approaches to thinking about chemistry. The evidence suggests even these students do develop enhanced reflective skills, and it is worth persevering when faced with resistance. A key goal of instruction in chemistry is to ensure students consciously connect ideas as a learning strategy, and this approach seems to facilitate this in a way that can be woven seamlessly into a teacher’s delivery.