ABOUT TEACHING -- #50

A Newsletter of the Center for Teaching Effectiveness
Spring 1996

A Comparative Study of Learning in Lecture vs. Problem-Based Format

Elizabeth M. Lieux,
Nutrition and Dietetics

The course that I have taught for 14 years, Quantity Food Production and Service, is required for most students in Nutrition and Dietetics and for all Hotel, Restaurant, and Institutional Management majors. The classes were getting larger, from about 20 students to over 80, and becoming much less fun to teach. I found that although my teaching evaluations were acceptable, they were not at the level of my other courses nor the level I had come to expect in this course. Although I tried to keep the lectures fresh with new stories, readings, videos, projects, and lecture notes, it was clear that student interest (as well as my own) was flagging.

After attending several workshops I thought that problem-based learning (PBL) might be a method to revitalize the course and me. I had concerns that many faculty have expressed about changing to PBL. I was unsure if we could "cover" as much material with the new method. I had always been satisfied with the quantity of important information I was able to provide to each class through lectures. Many dietetics students had commented that the information gained in this course had enabled them to perform extremely well on a nationally administered examination to become a Registered Dietitian. Would PBL allow dietetics students to continue to exceed the national mean in foodservice management?

I also gave some thought to teaching evaluations. I consider teaching to be the most important thing that I do and it was hard to imagine how not lecturing would continue to allow me to feel like a good teacher. Would students view my contribution to their learning as useful and valuable or would my teaching evaluations go down?

With these and other concerns in mind I decided to teach the course using the two methods of instruction and compare as many parameters as possible to determine whether lecture and PBL were equal in outcome. In the Fall of 1994 I offered two sections of Quantity Food Production and Service. Both were taught at 8:00 A.M. and both used the same learning objectives, textbook, and readings. The lecture section had 75 minute lectures interspersed with some videos, a small amount of group work, and one case. The PBL section had 10 problems which students worked on in groups for two class sessions each.

Research on Lecture Method vs. Problem-Based Learning Method

Research methods to compare process and outcomes included a pretest of knowledge about food and nutrition, a pretest and posttest of preferred learning environment, attendance records, qualitative assessment of classroom environment, student evaluations of the course using the Instructional Development and Effectiveness Assessment instrument (IDEA), and a common essay-type final exam composed of eight questions (students chose five to answer).

Independent and dependent t-tests plus Chi Square tests were conducted on the data to determine significant differences between the two methods of instruction. Stepwise regression of four independent variables (grade point average (GPA), section, major, gender) were significant predictors of dependent variables (learning environment pretest and posttest, knowledge pretest, and final exam).

Quantitative Results of the Study

The results of comparing the two instructional methods suggest there is no real difference in learning achieved between lecture and PBL methods nor does method of teaching change the preferred learning environment. Caution in interpreting regression analyses is warranted because of the small numbers of students available to be included in each model.

Twenty percent of the variance in knowledge of food and nutrition at the beginning of the course was explained by GPA, not section, major, or gender. This indicated that students in both sections were not different initially in their knowledge of the prerequisite information.

Eleven percent of the variance in the preferred learning environment was explained by section, not GPA, major, or gender for the pretest. Seven percent of the variance was explained by section for the posttest. Neither section changed their preferred learning environment as a result of taking the course.

Twenty nine percent of the variance in performance on the final exam was explained by the GPA and major, not section or gender. Students with higher GPAs and those majoring in Hotel, Restaurant and Institutional Management performed better in the final exam.

Therefore I conclude that learning important concepts in Quantity Food Production and Service is achieved equally using either the lecture method or PBL.

Attendance was significantly higher in the PBL class than in the lecture class. PBL students attended an average of 23.5 and lecture students 17.5 of 26 sessions. The implication of this data is that I had more opportunities to interact with students because they were more likely to attend PBL classes than lecture classes.

Course Evaluations

Whenever there are major changes within a course it is important for the instructor to get as much feedback from students about their perceptions of the effectiveness of the course as is possible. This was done using observations from an outside reviewer and through both informal and formal student evaluations. The results of student evaluations were not analyzed statistically but there are some interesting observations to be made which reinforced qualitative information provided by the reviewer and students. Students in the lecture class (58% completed the instrument) perceived they learned more than the PBL class (97% completed the instrument). All four parameters which comprise subject matter mastery in the IDEA instrument were above the 82nd percentile for the lecture class with two above the 92nd percentile. PBL students perceived that they learned less; two parameters measured were < 60th percentiles. This perception is not supported by the results of the final exam which show equal learning with both methods. I believe that there was discussion outside of class between students in both sections comparing what they were learning. PBL students identified that they were covering less material than lecture students so they assumed they were "learning" less.

PBL students perceived they developed thinking and problem solving skills (91st percentile) as compared with lecture students (71st percentile). Additionally PBL students perceived development of effective communication skills (89th percentile) and sense of personal responsibility (90th percentile), results which were not perceived by students in the lecture method. This outcome is most gratifying because thinking, problem solving, and communication skills are essential in the graduates of both programs.

Both sections of students provided approximately the same rating for course description parameters although PBL students perceived they worked somewhat harder than lecture method students. The rating as to whether they would like the instructor again was exactly the same (3.7 on a scale of 1-5).

The main area of guidance derived from the student evaluations that caused me concern related to my communication of content and purpose. Students in the lecture method were much more satisfied with my demonstration of the significance of the subject, summarization methods, communication of course objectives, and explanations than were students in the PBL section. This reinforced subjective comments by the PBL students that they wished they had more lecture.

Results of Evaluations

Since this first offering of the course I have developed several tactics to provide more support and structure for the PBL students. Now, I briefly introduce each problem, provide more direction as they are working through the problems, and do a wrap-up of the important points they should have addressed in each problem. This has given the majority of students who have a preferred learning environment that tends to be more teacher-centered than student-centered the confidence to explore unknown areas.

Student evaluations were initially very useful to help identify an area where I could provide much needed help. Now the evaluations are confirming that good teaching is not only lecturing but providing an environment and interesting materials to allow the student to explore, learn, and grow in teams. My teaching evaluations continue to improve and I'm having much more fun with this course because I can see the students working through the problems and developing group process, research, and communication skills. Most are more interested and active learners than students in the lecture method, and the classroom is a lively place to be.


"http://www.udel.edu/pbl/cte/spr96-nutr.html"
Last updated Feb. 20, 1997.
Copyright Elizabeth M. Lieux, Univ. of Delaware, 1996.