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A Modular Approach to Organic Chemistry Laboratory
Jennifer Swift, Ph.D.
Department of Chemistry, Georgetown University
In Spring 2004, the format of the Organic Chemistry II course was redesigned so that experiments could be performed as a set of four conceptually connected multi-week “modules.” The new format was developed as a balance between the practical challenges of class size and existing facilities and the possibility of achieving deeper and or slightly different student learning goals.
Background
Organic Chemistry Laboratory II is a large (~150 student) course required of chemistry and biochemistry majors, as well as all premedical students. The traditional format of the laboratory course, as at many other universities, consists of a series of one-week experiments in which students carry out discreet “cookbook” 4-hour experiments.
While this approach has several logistical benefits (e.g. ease in handling large numbers of students, relatively low experimental costs, experiments that usually work), a number of studies have shown that this format is not good at promoting deep understanding of the actual chemistry due to the students' limited intellectual engagement with the material.
Knowledge Survey
An online knowledge survey was administered at the beginning and end of the semester. The survey consisted of 49 proposed tasks and 5 sorting questions (e.g. declared major, year, sex, previous grade in fall courses). Students were asked to rate their confidence level in performing a given task according to a 3-point scale where 1 = high and 3 = low. Tasks were based on the following areas:
- (1-10) Recognition of different phases of matter
- (11-17) General experimental methods
- (18-27) Instrumentation
- (28-35) Specific syntheses
- (36-39) Library searching
- (40-47) Science writing skills
- (48-49) Experimental design
The optional survey, administered in January and May, was completed by a large fraction of the students (110, 72.8%). The tasks with the greatest and smallest changes were examined against the course content. In most cases, the results were not surprising. The survey will be reimplemented in Spring 2005.
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Specific Goals
- Emphasize organic chemistry in the “real world”
- Collectively generate original research data
- Develop students’ scientific writing skills
- Investigate new learning assessment tools
The Modules
(1) Dye Synthesis and Dyeing (2 weeks):
Each student synthesizes two of four different dyes, shares samples with a lab partner, and dyes pieces of multifiber fabric with each. The students are asked to evaluate the types of intermolecular interactions between the various dyes and fibers.
 In the infamous line in the 1967 movie The Graduate, Dustin Hoffman is told "There is a great future in plastics." Who knew he was thinking about Nylon Synthesis (Mrs. Robinon's pantyhose) at the time...
(2) Standard vs. “Greener” Nylon Synthesis (3 weeks):
Students synthesize adipic acid via two different methods. The first week’s protocol is easier than the second, but generates more hazardous chemical waste that is costly to remove. Students are asked to compare and contrast the two syntheses, both in terms of the pure chemistry and industrial scaleup.
(3) Polymers, Gels & Crystals (2 weeks): weeks): In this original research experiment, the students prepare gels infused with high concentrations of amino acid molecules. Over a period of a few days, amino acid crystals spontaneously appear. Each student removes the crystals from the gel, and analyzes them to see whether more left- or right-handed crystals formed. The entire class’s data is subsequently analyzed to see if there is a statistical bias. The gel methods under development may one day be important for the separation of pharmaceutical compounds.
(4) Now I See the Light (3 weeks):
weeks): Students synthesize a light protection (sunscreen) agent, use light to perform a dimerization reaction, and generate light in a chemiluminescence experiment. UVA & UVB irradiation as well as the virtues and vices of suntanning salons are discussed.
Writing
Instead of conventional (and somewhat regurgatory) laboratory reports, students are asked to write their experimental sections in a style that is consistent with a typical professional journal. In later modules, students are also required to write abstracts in journal format style. A more detailed examination of the student writing samples is still needed in order to determine whether actual improvement in writing was achieved.
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