Posted on behalf of Aaron Finke

Chemistry lab courses should focus more on method and problem-solving rather than specific techniques, with room for students to "fail" so they can learn from their mistakes. The best approach is to use open-ended experiments that require students to formulate conclusions other than "it worked" or "it didn't work." However, these experiments usually require a significant time commitment on the instructors' part, and so these kinds of experiments are usually only found in labs for chemistry majors with small student enrollments.

My undergrad's senior capstone project for chemistry majors is a particularly good example of this kind of open-ended science project. In our instrumental analysis lab, teams of three or four were given an item the coordinators purchased from the store — a calculator, a bottle of glue, etc. We were then given questions to answer, such as the identity of the polymer in the packaging, trace metal analysis of the can, the propellant, and so on, which required us to use the instruments and techniques we learned in the semester. Since nobody knew the “correct” answer, sufficient statistical analysis was required to pass muster.

This project was one of the highlights of my undergraduate curriculum, but it required considerable time and effort on the TA's part- and we had 5 TAs for about 30 students. How can large universities undertake such a project in a lab class with 500 students and 10 TAs?

Melanie Cooper, a professor at Clemson University, has spearheaded a program there to develop a high-enrollment laboratory course that is open-ended and focuses on method and reasoning rather than techniques. In a 2006 J. Chem. Ed. paper (vol. 83, p. 1356), she describes an example project for an organic lab. Each student was given an unknown, and after characterization of the unknown, the student would have to find a procedure for nitration of that unknown using the chemical literature, and justify that procedure before attempting it. Students monitored the reaction by TLC, and noticed that some unknowns reacted faster than others, and some even decomposed if the temperature was not controlled. Students could then collaborate and determine what factors led to such a disparity in reactivity, drawing from concepts learned in lecture and from each other.

This is the kind of project that requires students to think about what they are doing, rather than simply read off a recipe they are given. Furthermore, in such an open-ended project course, there is room for experiments to fail — a luxury that "cookbook" labs, scrambling to finish as many experiments as possible in a semester, do not always have.

Science is a humbling process — most scientists expect some portion of experiments they perform to fail. However, in today's "cookbook" labs, failure to perform the experiment adequately leads to a lower grade in the course, leading many students to believe that all practical science is based in absolution — when an experiment fails, it is your fault, no matter what. (Then some of these undergrads join research labs, and have to learn the hard way that cutting-edge science doesn't work like that!) Open-ended lab experiments give students the opportunity to perform “real” science in a more controlled environment.

Posted by Neil Withers at 05:43 AM | Permalink | Comments (0) | TrackBacks (0)

[Joining The Sceptical Chymist is our latest guest blogger, Aaron Finke. A grad student at the University of Illinois, Urbana-Champaign, he works on polyphenylene dendrimers and hyperbranched polymers. You may know Aaron better as Excimer from his posts at Carbon-Based Curiosities.]

I will be focusing most of my energies on these guest-blogging posts to chemical education. This past semester, I had the opportunity to be in charge of a large laboratory course — specifically, the organic chemistry lab course for non-chemistry majors. The "behind-the-scenes" experience I got was an eye-opening one in many ways, from a pedagogical, professional, and personal perspective. I will attempt to recount my experiences and lessons learned here.

A large portion of the students in my lab course were pre-medical and pre-veterinary students, and took it to satisfy the requirements for getting into their respective programs. A majority of the students took this course with the full recognition that it was merely a hurdle for them — a hoop to jump through with no relevance to the future careers to which they are aspiring.

I can't blame them for having that mentality. The course is an organic chemistry laboratory course, designed to introduce procedures and methods in the synthesis and purification of organic molecules... skills that are mostly irrelevant to those outside of organic chemistry. They learn and perform techniques like extraction, column chromatography, recrystallization, basic organic synthesis, and so on. I use a majority of these techniques every day. But I am an organic chemist. The 500 students in my class are not. It is highly unlikely they will actually use the specific skills implemented in the course, unless they plan on distilling their own whiskey! [Editor's note: This is illegal in many countries]

The skills students SHOULD be learning in laboratory classes are more general, and, with a "cookbook" chemistry curriculum, are not developed in any capacity. A report which came out June 4, co-authored by the Association of American Medical Colleges (AAMC) and the Howard Hughes Medical Institute (HHMI) and entitled "Scientific Foundations for Future Physicians", outlines eight core competencies that pre-medical students should demonstrate before entering medical school.

The second competency listed concerns lab courses: "[The student should] demonstrate understanding of the process of scientific inquiry, and explain how scientific knowledge is discovered and validated." Interestingly, the guidelines indicate only three chemistry-specific goals: gathering primary data for mixtures of compounds, using stoichiometric analysis to determine yield, and, most interestingly, demonstrate a knowledge of instrumentation such as NMR, mass spec, X-ray, etc. These goals, ideally, should be implemented with a focus on discovery, making conclusions, and understanding error.

Most pre-med organic chemistry lab experiments focus on only one of those three things — characterization without application; or synthesis without full characterization — and I dare say few, if any, display a heavy focus on instrumentation. This report acknowledges that advances in medical science and medicinal chemistry rely heavily on modern instrumentation, and yet outdated chemical identification methods are more heavily emphasized in most basic lab courses. When was the last time anyone had to make a semicarbazone derivative of a ketone outside of a lab course? These are secondary or tertiary methods of identification to modern organic chemists. It is enough to know that they exist. But if medical students are to understand the modern literature, they should be taught modern chemical methods. And in their o-chem labs, they are not.

In my next post, I’ll discuss what some chemistry educators are doing to fix the problem of relevancy in lab courses.
[Posted on behalf of Aaron Finke]

Posted by Neil Withers at 06:05 AM | Permalink | Comments (4) | TrackBacks (0)