Essential Learning Outcomes for Delocalization (Resonance) Concepts: How Are They Taught, Practiced, and Assessed in Organic Chemistry?

The concept of delocalization (i.e., resonance) is fundamental concept in organic chemistry but essential learning outcomes (LOs) have not previously been proposed nor has there been an analysis of how resonance is taught, despite indications in the literature that students have many non-canonical ideas about the concepts. To address this deficit, we first developed a set of ten learning outcomes believed to be essential to the concept of delocalization in organic chemistry, especially for students' later success. Next, we analyzed how these learning outcomes are being taught, practiced and assessed in common textbooks and in a sample of exams. Five themes emerged from the analysis: (1) several of the essential intended LOs we identified are not represented in the textbooks' teaching explanations, practice questions, or professors' assessments; (2) the concepts related to delocalization are often taught, practiced, and assessed without associated justifications; (3) there is a large gap between when delocalization is taught and when it is used in context; (4) the link between delocalization and other concepts (e.g., reactivity) is not explicitly explained in most teaching materials; and (5) the language used around delocalization may be misleading (e.g., resonance, stability). Our analysis identified areas in which delocalization education could be improved, including with respect to teaching, practice opportunities, and assessing the concepts.