Classroom Techniques
Incorporating a Modified Problem-Based Learning
Exercise in a Traditional Lecture and Lab-Based
Dairy Products Course
Andrea M. Liceaga, Tameshia S. Ballard, and Brent J. Skura
Abstract: A modified problem-based learning (PBL) exercise was implemented in a food science Dairy Products course,
which had previously been taught in the traditional lecture and laboratory format only. The first 10 wk of the course
consisted of weekly lectures and laboratory exercises. During the remaining 3 wk, students were presented with a case
study that described milk quality problems that could be encountered by the dairy industry. Each week, students received a
set of case disclosures containing relevant information that assisted in solving the case. Students were asked to present their
findings at the end of the course in the form of a written “consultant’s report.” In addition, students were given a survey
asking for feedback on the PBL exercise, and the usefulness of having the lectures and labs prior to the PBL experience.
Eighty percent of the students found that lectures and labs provided them with sufficient background knowledge to
understand and solve the PBL case, 70% found that the PBL reinforced course material covered during lecture and labs,
50% responded that PBL helped them develop new ways of reasoning about the subject matter and 65% reported that
PBL taught them to think critically. Of the total students surveyed, 56% would prefer to participate in similar types of
PBL exercises in the future. Incorporating PBL into traditionally taught food science courses can have a positive influence
on the learning process.
Introduction
The concept of problem-based learning (PBL) was initially developed in the mid-1960s by a group of educators at McMaster
Univ. Medical School in response to a need to increase the critical
reasoning skills of young physicians graduating from their program (Gallagher and others 1995). PBL has gained popularity in
recent years as an alternative to the traditional didactic approach
where student learning is predominately driven by the teacher.
In PBL, teachers must prompt students to take on responsibility,
encourage independence, and then fade into the background and
become another colleague on the problem-solving team (Ward
2002). According to Tan (2004), adopting PBL will usually involve 3 shifts from the traditional teaching paradigm, namely, (1)
content coverage to problem engagement; (2) role of lecturing
to role of coaching, and (3) students as passive learners to that
of active problem solvers. Currently, PBL has spread into schools
of dentistry, pharmacy, and engineering, and there are growing
numbers of faculty at various universities who are changing their
curricula to a PBL format (Camp 1996).
MS 20100795 Submitted 7/14/2010, Accepted 11/15/2010. Authors Liceaga and
Ballard are with Dept. of Food Science, Purdue Univ., West Lafayette, IN 47907,
U.S.A. Author Skura is with Food, Nutrition & Health, The Univ. of British
Columbia, Vancouver, B.C. V6T 1Z4, Canada. Direct inquiries to author Liceaga
(E-mail: aliceaga@purdue.edu).
c 2011 Institute of Food Technologists®
doi: 10.1111/j.1541-4329.2011.00117.x
In PBL, learning occurs within the context of a complex,
“real-world” problem (Hmelo-Silver 2004). Instead of focusing on
content knowledge, PBL uses ill-structured problems to encourage self-directed learning where students can build on previous
knowledge to solve real problems. To be effective, PBL problems
must (1) be based on compelling real-world situations, (2) generate multiple hypotheses, (3) exercise problem-solving skills and
require creative thinking, (4) require knowledge that satisfy curricular objectives, and (5) be multidisciplinary in nature (Ram 1999).
The general belief is that if students are presented with a problem that is deemed relevant and has real-world application, their
learning will be deeper and more meaningful since it is knowledge
that they have constructed themselves within a context and in response to a need (Ram 1999). In a comprehensive review of PBL
by Norman and Schmidt (1992), it was concluded that PBL may
increase retention of knowledge and enhance both intrinsic interest in the subject matter and self-directed learning skills. Vernon
and Blake (1993) conducted a review that compared PBL to more
traditional methods of medical education and found that with
regard to student program evaluations and clinical performance
and knowledge, the data consistently favored the PBL approach,
although academic achievement data tended to favor traditional
educational methods. Ram (1999) reported that PBL was an effective way of motivating undergraduates in a chemistry course to
learn and enjoy the learning process. It is generally accepted that
PBL is popular with students, promotes lifelong learning skills, and
Vol. 10, 2011 r Journal of Food Science Education 19
Modified-PBL in a Dairy Products course. . .
likely does not sacrifice important areas of knowledge, although
more studies are needed to truly evaluate its overall effectiveness
as compared to traditional learning models (Colliver 2000; Clark
2006).
Despite evidence suggesting the potential benefits of PBL, there
have been very few published studies on its use in food science
courses. Duffrin (2003) incorporated PBL into an introductory
food science course and found that PBL aided students in developing communication, problem-solving and self-directed learning
skills, and has the potential to be an enjoyable and challenging
classroom experience for both students and teachers. The objective of this article was to provide an example of the use of a
modified version of PBL in an upper-level undergraduate course
in Dairy Products, and to share some of the students’ perceptions
and instructor observations on the PBL exercise.
Background Information on “Dairy Products”
Dairy Products is a junior-level course that is primarily taken
by animal science and food science majors. In this course, students
are introduced to fundamental concepts associated with the production of various Dairy Products (fluid, cultured, and dried milk
products, butter and frozen milk products). Some of the concepts
covered in the course include milk production, milk chemistry
and microbiology, dairy processing equipment, and common unit
operations. The focus of the course is the association between
fluid milk quality (that is, chemical and microbiological), process
operation (that is, “process-ability” of fluid milk), and final product quality (that is, texture, flavor, and so on). The course has
previously been taught in the traditional lecture and lab format,
with 1.5 h of lecture and 2 h of lab each week. The PBL exercise
was intended to complement the material covered in the lectures
and labs. Participation in the PBL exercise and the written PBL
case report were factored into the final grade.
Materials and Methods
The Dairy Products course was instructed in 3 different formats
(lecture, laboratories, and PBL). The first 10 wk of the course
consisted of weekly lectures and laboratory exercises where students were able to apply the knowledge and concepts learned from
the lecture. During the final 3 wk of the semester, students were
divided into groups of 4 for the PBL sessions and presented with
a case study that portrayed milk quality problems that could be
encountered by the dairy industry (Table 1). The lecture and lab
portions of the course were completed prior to starting the PBL
exercise. Student participation in the PBL exercise was mandatory,
although completion of the survey was voluntary (IRB approval
number 0900008549). The learning outcomes of the PBL exercise
were to (1) practice verbal and written communication skills; (2)
gain experience in working as a group in solving a problem of
practical importance in the food (dairy) industry; and (3) practice
critical thinking and problem-solving skills. Each week, students
received a set of case disclosures containing relevant information
that assisted in solving the case. During the PBL sessions, the instructors and teaching assistants (TA) acted as facilitators of the
learning process. A series of guiding questions were included with
each of the disclosures. Any questions that the students could not
answer were considered “learning issues,” and they would have
to research those topics independently outside of class hours and
present their findings to the group the following week (HmeloSilver 2004). In addition, after each disclosure, students were encouraged to write letters to the “Plant Manager” associated with
the case to ask questions and seek further clarification. The letters allowed students to practice written communication skills in a
professional setting. Instructors would read the letters and respond
back to the students as the “Plant Manager” the following week.
In order to make the case study seem more real, a quality assurance
manager from an actual dairy processing company that had been
familiarized with the case visited the class to provide additional
information and answer questions for the students.
At the end of the 3 wk, each group was asked to present their
findings by writing a 1500 to 2000 word “Consultants Report” submitted on the last day of classes. The report was required to address
the problem(s) identified by the group and to make recommendations to the company for rectifying the problem(s). The criteria
for assessing the report were based on 5 categories: (1) discussion
of milk processing, microorganisms, and product spoilage as it is
related to the case—40 points; (2) presentation style—15 points;
(3) clarity and impact of writing—20 points; (4) organization—10
points; and (5) thoroughness and originality—15 points. Students
were asked to complete a PBL evaluation form, where they were
able to evaluate their peers in the PBL team as well as their participation. This evaluation was factored into their final grade. In
addition, students were asked to complete a survey on the PBL
exercise and the usefulness of having the lectures and labs prior
to the PBL experience (Table 2). The survey was developed in
consultation with faculty in Youth Development & Agricultural
Education at Purdue Univ.
Results and Discussion
In this course, we decided to incorporate a modified version of
PBL where content knowledge in the form of lectures and labs
were provided prior to the PBL exercise. However, students did
not receive lectures or participate in labs once the PBL case began.
This approach was different from what is traditionally considered
as PBL where learning begins after students are confronted with
an ill-structured problem (Gallagher and others 1995). Our results
from the PBL survey (Table 3) indicated that 80% of the students
Table 1–Problem presented in the PBL case study.
found that the “lectures and labs provided them with sufficient
Problem statement
background knowledge to understand and solve the PBL case.” In
Dutch Meadows Dairy Processors, a milk processor located at Pitt Polder, Ind., addition, 70% of students responded that “PBL reinforced course
has received a series of consumer complaints about pasteurized milk.
Consumers are stating that the milk has a fruity like odor and in some cases material covered during the lectures and labs.” A limitation of
there have been reports of bitter and fruity flavors with apparent curdling traditional PBL deals with students’ concerns over self-directed
of the milk in some instances. Consumers have been calling the main
learning in terms of frustrations with the lack of foundational
switchboard of the processing plant and have also been returning milk to
knowledge, and where to look for the information needed to
retail stores. Management of the retail chains, which are Dutch Meadows
Dairy Processors largest customers, are threatening to cancel the supply
solve the problem (Vernon 1995; Tan 2004). In agreement with
contract with Dutch Meadows Dairy Processors if the problem is not
immediately rectified. The retail chains are beginning to notice lower sales Tan (2004), there are disciplines and subjects where foundation
of Dairy Products and fewer customers in the stores compared to several
knowledge is best disseminated first, as effective PBL requires the
weeks ago before the problems first started to occur.
activation of prior knowledge. Therefore, it may be necessary in
20 Journal of Food Science Education r Vol. 10, 2011
Available on-line through ift.org
Modified-PBL in a Dairy Products course. . .
Table 2–Survey on students’ perceptions on the PBL exercise.
Instructions: Please
indicate your personal
opinion about each
statement by circling the
appropriate response at
the right of each
Strongly Somewhat Somewhat Strongly
statement.
disagree disagree
agree
agree
1. The lectures and labs
1
2
3
4
provided me with
sufficient background
knowledge to
understand and solve
the PBL case.
2. I would have been
1
2
3
4
able to understand
and solve the PBL case
without the lectures
and labs.
3. PBL reinforced course
1
2
3
4
material covered
during the lectures
and labs.
4. I prefer the PBL format
1
2
3
4
over lecture and labs.
5. PBL helped me to
1
2
3
4
develop new ways of
reasoning about the
subject matter.
6. PBL helped me to
1
2
3
4
understand the
realities of working in
the real world.
7. PBL helped me to see
1
2
3
4
the relationships
between complex
content.
8. PBL helped me to
1
2
3
4
think differently about
the content.
9. PBL taught me how to
1
2
3
4
think critically about
the subject matter.
10. PBL increased my
1
2
3
4
ability to effectively
work in a team.
11. PBL encouraged me to
1
2
3
4
make learning
connections with
other students.
12. PBL engaged me in
1
2
3
4
the learning process.
13. If given a choice, I
1
2
3
4
would prefer to
participate in similar
types of PBL exercises
in the future.
General questions:
1. What part of the PBL exercise did you find most interesting? Explain why.
2. What part of the PBL exercise did you find most challenging? Explain why.
some instances to deviate from the so-called “pure” PBL in favor
of a modified version where students are provided with some basic
background knowledge, such as what was done in this course.
Despite 80% of students commenting that lectures and labs provided them with sufficient background knowledge to solve the
PBL case, only about half (56%) of them responded that they
would prefer to participate in PBL in the future. This finding may
be due to the students’ general unfamiliarity with PBL, which can
result in anxiety. The anxiety can be attributed to the fact that
students were unsure if they would be as successful with PBL as
they may have been in the more traditional teaching model that
they were accustomed to (Peterson 2004). To alleviate some of the
anxiety associated with encountering PBL for the first time, Peterson (2004) has found it helpful to spend the majority of the 1st
Available on-line through ift.org
Table 3–Student responses to questions in PBL survey.
Nr of SWA
and SAa
Survey questions
1. The lectures and labs provided me with sufficient
background knowledge to understand and solve the PBL
case.
2. I would have been able to understand and solve the PBL
case without the lectures and labs.
3. PBL reinforced course material covered during the
lectures and labs.
4. I prefer the PBL format over lecture and labs.
5. PBL helped me to develop new ways of reasoning about
the subject matter.
6. PBL helped me to understand the realities of working in
the real world.
7. PBL helped me to see the relationships between complex
content.
8. PBL helped me to think differently about the content.
9. PBL taught me how to think critically about the subject
matter.
10. PBL increased my ability to effectively work in a team.
11. PBL encouraged me to make learning connections with
other students.
12. PBL engaged me in the learning process.
13. If given a choice, I would prefer to participate in similar
types of PBL exercises in the future.
43 (79.6%)
12 (22%)
38 (70.4%)
28 (51.9%)
27 (50%)
40 (74.1%)
36 (66.7%)
28 (51.9%)
35 (64.8%)
22 (40.7%)
27 (50%)
36 (66.7%)
30 (55.6%)
a Responses represent the number of somewhat agree (SWA) and strongly agree (SA). Brackets
represent mean percent responses for N = 54.
class period emphasizing 3 things before introducing PBL: (1) the
basic definition of learning; (2) the difference between a teachingcentered paradigm and a learning-centered paradigm, and (3) the
concept of adult learning, although he asserts that some level of
anxiety is needed if PBL is to be successfully implemented. Although we did provide a brief introduction to PBL during the
1st class, when teaching this course in the future, we may want
to consider providing more details on the educational theory behind PBL, and more clearly define the roles and expectations of
both students and instructors. In addition, instructors and/or TA
involved in PBL should receive some form of training on how
to facilitate PBL group discussions in order to allow students to
respond better and enrich their experience in the PBL exercise.
In this instance, instructors and TA did not have the specific PBL
training, but did have previous experience in implementing PBL.
One of the main criticisms of the traditional teacher-centered
paradigm is that it does not adequately prepare students to think
critically. Instead, students are considered passive learners relying
on the instructor for the majority of their knowledge (Tiwari and
others 2006). PBL, on the other hand, has been praised for its
potential to increase students’ critical thinking skills (Birgegård
and Lindquist 1998; Antepohl and others 2003; Tiwari and others
2006). We found that 65% of students agreed that the PBL exercise
taught them to think critically about the subject matter. Comments from the students revealed that the PBL challenged them
to reflect on the information given in class and allowed them to
expand on that information (Table 4). This was evident in the written “consultant’s reports,” where in addition to practicing verbal
and written communication skills, several of the groups demonstrated in-depth knowledge of the case and provided thoughtful
reasons for the problem as well as logical recommendations for its
resolution.
From the survey comments, it was found that only 41% of students felt PBL increased their teamwork ability and 50% of them
thought that the PBL exercise encouraged learning connections
with other students. This is not uncommon as other instructors
have found that PBL discourages group members from active participation. Possible reasons include that students are faced with
Vol. 10, 2011 r Journal of Food Science Education 21
Modified-PBL in a Dairy Products course. . .
Table 4–Student comments about the PBL exercise.
What part of the PBL exercise did you find most interesting?
“The way it is connected to real life because you could apply it.”
“I found the case to be interesting because it connected much of what we
learned.”
“The PBL challenged me as an individual to reflect on information given in
class and expand on that information.”
“I liked the problem solving nature of PBL. Being given new information
and working with it weekly to reach a conclusion was more engaging
than the lectures or regular labs.”
“I liked the way it was treated like a real life situation.”
“The fact that we got to apply our knowledge in a real work setting was
nice. A lot of classes don’t do that.”
“It made you think and actually was something that is very relevant in the
real world.”
What part of the PBL exercise did you find most challenging?
“Narrowing down the huge amount of research our group came up with
and deciding which material was relevant to the case.”
“Researching the stuff not covered in class.”
“Getting together in groups.”
“Working in a group.”
“Writing the report because there wasn’t much guidance.”
group members who do not equally commit to the project, do
not prepare for the group meetings or fail attend to attend them
at all (Dolmans and others 2001; Duffrin 2003).
Another common challenge in the PBL exercise was that the
students felt that there was not sufficient guidance on how to
write the report (Table 4). This seems to be a recurring issue with
other instructors who have integrated PBL into their classrooms,
with students wanting clearer instructions on the expectations of
the assignments (Duffrin 2003). As previously discussed, this is a
frequent request of students who are experiencing PBL for the first
time as this is a method that they are not familiar or comfortable
with (Duffrin 2003).
Finally, the majority of the students (74%) agreed and several
commented that an interesting part of the PBL exercise was the fact
that they were able to apply the knowledge learned in the course
to address a “real-world” situation that could be encountered by
the dairy industry (Table 4), which is one of the main goals of PBL
(Hmelo-Silver 2004). It became evident from the letters written
to the “Plant Manager” that the students were engaged in the case
as if they were real consultants trying to solve a real problem. In
addition, having an invited speaker from the industry attend one of
the PBL sessions further enhanced the “real-world” experience.
Conclusions
In this Dairy Products course, we found that by disseminating
knowledge through lectures and labs prior to the PBL exercise, we
were able to provide students with sufficient knowledge to solve
the PBL case. At the same time, students were able to develop
problem-solving and critical thinking skills within the context of
a real-world situation. A modified version of PBL could be a
22 Journal of Food Science Education r Vol. 10, 2011
useful tool to reinforce material covered in traditional lecture/lab
courses, and can be a positive influence on the learning process.
Further research is needed to evaluate the impact of providing
content knowledge before the implementation of PBL versus what
is considered traditionally structured PBL.
Acknowledgments
The authors would like to thank Dr. Neil Knobloch from the
Dept. of Youth Development and Agricultural Education at Purdue Univ. for his contribution in the development of the student
survey used in this study.
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