Student-generated annotated concept sketches provide an alternative approach for instructors to formatively assess students' understanding of environmental topics, such as photochemical smog and ozone layer depletion. The sketches are external representations of students' cognitive models. Results obtained from a group of 150 female students using an action research methodology, suggest that this method is effective in enhancing students' engagement and communication among peers. This further helps students to reinforce scientific theories and concepts. Furthermore, the data gathered also revealed alternative conceptions, misconceptions, and knowledge gaps in students' understanding and provides an opportunity for easy and immediate feedback. In this study, misconceptions define ideas that are in direct contrast with the accepted scientific conceptions, whereas alternative conceptions describe ideas that are incompatible but unconflicting with the accepted scientific conceptions. Students were actively engaged and showed the ability to express their knowledge in ways other than writing, which is especially useful in English Language Learner (ELL) friendly environments. Students were required to participate in the lecture by paying special attention to the source of pollution, environmental impact, and solutions to issues related to air pollution. The representational annotated concept sketches were completed individually or in groups of two to three students. Feedback was provided orally, and/or using a rubric designed to identify and highlight understanding, misconceptions, and knowledge gaps.