Evaluation of a Modified Keller Method in a Biochemistry Laboratory Course Lance E. J a c k m a n Department of Biochemistry and Biophysics, Iowa State University, Ames, IA 5001 1 The Keller Plan or Personalized System of Instruction has had an important impact on college science teaching ( 1 ) . As a result, numerous recent reports concerning the use of the Keller ~ l a in n chemistrv teachinr. exclusive of the laboratorv. are found in the literature (2-i2). The effectiveness of he Keller plan as used in many of these courses has been evalnated in terms of student grade distributions, scores on final exams or standardized chemistry tests, and the students' comments and opinions. From these evaluations the overall impression is that most students learn chemistry by the Keller plan a t least as well as by traditional methods of instruction. Some reports even conclude increased learning as a result of KelIer pian teaching (1,6,13-15). Unfortunately, there are few reports describing the Keller plan (or a modification of the Keller plan) in laboratory chemistry teaching (13, 14, 16-18). Although a few reports (19-22) describe the Keller plan in courses containing a lahoratory, the laboratory is usually not self-paced or mastery oriented. Because of the scarcity of data, the effectiveness of the Keller plan in laboratory chemistry teaching has not yet been extensivelv determined. This report describes a successful modified Keller method for teaching a hiochemistry laboratory course and evaluates the method's effectiveness. This method has been used twice in our undergraduate course. The strategy was to develop and try out the Keller method during the summer session, 1979, hecause fewer students are enrolled a t that time. and then to evaluate the method in a more srientific way during fall quarter, 1979. In the fall quarter enough students enrolled so that half could take the course via the Keller method while the others could take the course in a traditional manner. Therefore, a comparison between the two groups was obtained. The course, a one-quarter lahoratory for 3 credits, consists of several verification lahoratory experiments with optional independent projects during the final weeks. Until the summer session, 1979, the course contained two one-hour lectures and two two-hour laboratory periods each week; the lectures immediatley preceded the lahoratory periods. The prerequisite, which may be taken concurrently, is a biochemistry lecture course. For this. most students take our one-auarter Survey of ~ i o c h e m i s t ' in r ~ which Lehninger's "Short course in Riochemistrv" is the text. The student bodv taking the lahoratory course is heterogeneous. Some students are ma-iorina - in food and nutrition, some in the bioloaical sciences, while others are in preprofessional studies that will lead to medicine. The level of the course is considerably below that required for our hiochemistry majols. For most experiments the mathematical treatment of data is kept to a minimum. Many of the experiments were developed especially for this course and are contained in a lahoratory manual available through the Iowa State Univeristy Bookstore ("Biochemistry Laboratory Manual," Bernard White and Lance E. Jackman, 1979). No other text is required, hut Hill and Feigl's "Chemistry and Life" is recommended for students needing outside reading. The experiments focus on biochemical techniques like spectrophotometry, paper and thin-layer chromatography, electrophoresis, and ion exchange chromatography. Also included are clinical tests for carbohvdrates, the extraction and senaration of egg yolk lipids, and assays for vitamins C and A and for a varietv of blood comoonents. More details and ~ a r t i a l content of the course are descrihed elsewhere (23,24j.
Description of Experimental Design The modified Keller method used durinz the summer session allowed students to proceed in a self-paced manner. To accomulish this, the laboratory was usually open from 8 A.M. to 5 P.M. with either a teaching assistant orme in the lah or in close proximity for assisting students when necessary. For safety reasons unsupervised work in the lab was not permitted. Students were not required to prepare any more reagents than under the traditional method of instruction and were encouraged to work in pairs. The course was divided into eight successive experimental units, and students were required to master (at a 95-100% level) the hiochemical concepts and experimental techniques. No formal lectures were given, hut for each unit a detailed handout was distrihuted: ( 1 ) Aiochemicol Concepts. All the basic biochemical concepts necessary for an understanding of the experiments were given. Many of these concepts were a review or those normally taught during the prerequisite b&hemistry lecture course. ( 2 ) Exprrirnentnl Objectiues. The required experiment? from the laboratory manual (usually one, two, or three two-hour experiments) were listed along with special notes and instructions concerning how students were to work in the lahoratory. Reminders and safety considerations, such as the requirement to wear eye goggles, or special instructions,such as a change from the laboratory manual procedure, were given in this section. (3) Experimental Concepts. A specific list was given containing the kinds of data that students must generate in the laboratory. Instructions for plotting graphs or manipulating data were included. Questions pertaining to the specific laboratory experiments were asked.
At the start of the course. students were riven the first unit uate student mastery. (1) The Data Discussion. When a student (or pair) felt ready, an appointment was made with one of the teaching staff. During the discuasion the instructor checked over the student's data along with any accompanying graphs and calculations. During this 10- to 15minute chat, it was usually easy to ascertain whether or not astudent had achieved experimental mastery. Also, free questioning by students was encouraged. If mastery had not been attained, a student was asked to reevaluate data or repeat parts of an experiment. (2) Written Mastery Quiz. Once the data discussim was complete, each student took a short written quiz covering both the biochemical and experimental concepts. The quiz was evaluated in the presence af the student, who was allorved todefend or expand upon questionable answers. Students were allowed to repeat quizzes when needed.
Once the experimental units were complete, a comprehensive final exam was given and (for the summer session, 1979) evaluated with the student present. Questionable parts of the final exam could be repeated. To emuhasize the i m ~ o r t a n c of e not urocrastinatina, each student was given arecommended time schedule. Even though slower students would he allowed to finish durina the next beginning of the course. Every student finished by the end of thc summer session and earned an A. I had some misgivings about giving all A's, but the course was designed in such a way that an A was Volume 59
Number 3
March 1982
225
guaranteed provided the student completed the course. Students normally do well in this course; the average grade has been a B. It was decided to attempt to determine whether or not the modified Keller plan as used in this course did increase student performance and justify the increased grades. Toward this end the following changes were made for the fall quarter, 1979. The students were divided into two groups. One group (group I, the control) took the traditional course-that is, a highly structured teacher-paced lahoratory course with the lectures preceding the lahoratory periods. Four quizzes were given, and students were required to write lahoratory reports on most experiments. The quizzes emphasized experiments for which no lab reports were required. Grades were determined from total points based uuon quizzes. lab reports. . . and the final exam. Even though students earnedpoints on quizzes and lab reports, they were still required to score a minimum of 80% on the final exam for an A: The other group of students (grouu 11, modified Keller made, and two experiments were added to account for the longer fall quarter. The final grade was determined using a point system. Each completed unit was worth a specified point value, but after completion of all eight units, the student was still required to earn a minimum of 80% on the final exam for
studies majors, etc., that group I1 had. Otherwise the selection process was entirelv a t random. The mean cumulative made point average (GPA) of group I was nearly identical to the GPA of . grouu. I1 (see table), indicatinz- the two croups were similar in ahility. Each rrouu uerformed exactlv the same exueriments. The materia&iveito group I (control) during theiectures was, as much as possible, the same material mouu I1 (Keller) students were expected to learn from the uni
