As the semester comes to a close, I have been reflecting on my lectures and experiences with a mechanistically organized course. The Karty text has presented many different types of reactions; from all of the reactions, I want the students to be aware of the central theme in ALL organic mechanisms. In every step, there will be a nucleophile and electrophile. Upon completion of the course, I want students to see this as part of the big picture.
Teaching a mechanistically organized course has many benefits. For example, I am able to spend less class time on nomenclature. This semester, I assigned nomenclature “chapters” 1-3 for the students to read outside of class, arranging them among chapters 1–10 of the text. This meant that I spent only 25% of lecture time explaining nomenclature. This absolutely does not mean that nomenclature is less important in an organic chemistry course. Rather, my goal is to keep the audience captive as long as possible while in the classroom and spend more time on the details of a given reaction or topic.
Students at Western Washington University are first introduced to the concept of molecular orbital theory in Organic Chemistry I. It is briefly mentioned in the general chemistry textbook, but it is excluded from covered content in first year classes. First year chemistry students are introduced to the concept of atomic orbital hybridization, but with surface level learning objectives. Objectives are typically assessed by simply having the student label the hybridization of a specified atom. Because of such a limited exposure, most students find themselves completely overwhelmed with the topics of hybridization of atomic orbitals and molecular orbital theory when they get to organic chemistry. Historically, the topics are covered at the beginning of the year-long series, only to be forgotten and rarely (if at all) applied to the numerous reactions that are covered. Feedback from past students has included statements of, “I just memorized how to assign hybridization, I don’t actually know what it means” and “Molecular orbital theory was the most confusing part of the course, I still don’t know why we learned it.”
Proton transfer reactions are described in Chapter 6 of Karty and are the students’ first experience with a general reaction. When introducing this material to my students last week, they were a little nervous when I said the word “reactions.” I told them that my job, in guiding them along their organic chemistry journey, was to help build their expertise in determining the direction of an overall reaction. I told them that their text presents this material in a simple step-wise mechanism, and that they would be “getting their feet wet in the shallow end of a swimming pool.”
When I was an organic chemistry student, I learned from a functional group based textbook. Fast forward fifteen years, and I was teaching organic chemistry from a functional group based textbook. As a chemistry department, it was what we knew and what we were comfortable with, but the department as a whole was ready for a change. Student retention and general enthusiasm for organic chemistry was low. Common feedback from students included “too much memorization” and “I took a quarter off, and I don’t remember anything I learned in Organic Chemistry I.” I remember feeling exactly the same way after I took organic chemistry. I memorized all the required reactions and then promptly forgot them once the quarter was over. Our goal, as a department, was to switch to a method of teaching chemistry that would take emphasis off memorizing reactions and instead would encourage students to apply mechanistic principles to a reaction to figure out the products formed. After about a year of discussions, the big switch to a mechanistically-organized textbook, Karty, was implemented at Western Washington University.
I think one of my biggest hesitations with changing textbooks and approaches was the amount of work involved with prepping a new course. While all the content would essentially be the same, the arrangement and presentation would be different. Lecture slides would need to be rearranged or remade to match the chapter order and contain figures from the new text. The expected amount of work seemed daunting, especially at the beginning of the academic year.
Expecting a huge undertaking, I started prepping lecture slides two weeks before classes were scheduled to begin. So far, I have prepped chapters 1 through 4 and I cannot stress enough how smooth the preparations have gone. In the past, while using a functional group based organic text, I had to rearrange chapter sections in order to improve the delivery of the material. There was absolutely no need to do that with the beginning chapters of the Karty text. The order and length of each chapter works so well that there was no need to make any adjustments.
Typically, I do not use a lot of slides during my lectures and the slides I do use do not contain a lot of text. Because this is my teaching style, I was expecting to get very little use from the pre-made lecture slides available in the instructor resources. This was absolutely not the case! I was easily able to use the pre-made presentations and simplify them to work for me.
The final key piece that has made the “new class” preparation easier has been the instructor guide. I am able to reference each section of the text in the instructor guide and it has a breakdown of the content, in-class questions, and interesting way to present topics. For example, there is a clever way to help students remember the dash-wedge notation for drawing 3-D tetrahedral geometries. I am really looking forward to using this resource as I prepare more chapters.
The prep-work involved in preparing a new class was one of my big concerns about switching to a new approach, but it was much easier than I anticipated. The chapters are laid out well in Karty and the instructor resources are excellent. It has been a smooth transition so far!
-Jennifer Griffith, Western Washington University
Click here to learn more about Prof. Griffith
When talking with chemist friends about their organic chemistry experience as students, many of them remember the mechanism questions as the most difficult; the last questions on each exam, the “A-student versus B-student” questions, were always mechanisms to struggle through. When I’ve explained that my school follows a mechanistically driven approach to organic chemistry, the response is sometimes one of surprise. Why are you making a tough subject even more difficult by focusing only on the difficult stuff? Doesn’t this make the course too high a level for most of your students?
We made it to the final chapter: Chapter 26 (“Polymers”). Each student is filled with a sense of pride that they have read every chapter in their textbook. Chapter 26 allows us to review mechanisms from throughout the text with real world applications. These applications are good preparation for next week’s final. In discussing them, I tell my students, “It is time to drink some coffee, put socks on, and wear some stylish pants.”