Reactions

Letters to the editor

Flipped classrooms

This letter is in response to the article “The Flip Side of Flipped Classrooms” in the Jan. 20, 2020, edition of C&EN by Claire L. Jarvis (page 23). It is clear that active learning and flipped classrooms can be very successful, especially for chemistry majors and highly motivated nonchemistry majors. Students can augment online lectures by conducting internet searches on almost any topic, find worked examples on YouTube, and share their homework efforts with other students via their computers or smartphones. That being said, I found during my 26 years of teaching general chemistry that students need to be taught the more difficult topics in chemistry first to get them started. Then armed with the initial concepts and methods we teach, they are much more likely to dive into active learning successfully.

In recent years I brought practice problems on paper to my lectures and passed them out to each student, who worked on the problems in groups at appropriate times during the lectures. I would give hints on how to work problems and have students write correct solutions on the board. That way, every student would have all the problems and solutions to take with them when class was over. I also frequently performed in-class demonstrations, such as those on gas laws, acid-base reactions, and redox. For instance, reacting a weighed amount of sodium bicarbonate with a certain number of drops of 3 M hydrochloric acid not only had the visual effect of carbon dioxide bubbling up but also functioned as a lead-in to many possible stoichiometric calculations.

Another active-learning tool consisted of take-home exams that included correct answers or solutions to every question and were available for students to copy. Students frequently told me that these exams were a great help for them in learning the material and doing well on actual exams. In addition to active learning in lecture, general chemistry lab had a minimum of 12 experiments per semester in which students worked hands on in pairs or larger groups to apply the topics we covered in lecture.

In closing, I encourage instructors, no matter how much and what methods of active learning you choose, to make that initial step of teaching your students in class the more difficult topics of chemistry.

Paul D. Thompson
Prestonburg, Kentucky