The article compares the effectiveness of problem-based learning (PBL) and traditional lecture-discussion instruction for teaching macroeconomics to high school students. Researchers found that PBL students performed significantly better on a knowledge test than students in traditional classes, with an effect size equivalent to a 4% difference in percentile grades. PBL was also more effective for students with high interest in economics and mid-to-low verbal ability, though both instructional methods led to similar outcomes for students with high verbal ability. The study provides support for using PBL to meet Ontario curriculum goals of developing inquiry, problem-solving and collaboration skills.

1. Daniel Genesee Ero Siouga—SP10
Standard of Practice and Professional Readings
Standard of Practice selected: B—Professional Knowledge
#1 Knowledge of the student
c) how teaching is shaped by what is known about
human development and learning
AND
#3 Knowledge of teaching practice
g) collaborate and structure interaction among students
to ensure that shared learning, as well as individual
learning, occurs
Article Selected:
Mergendoller, J.R., Maxwell, N.L., & Bellisimo, Y. (2006) "The Effectiveness of
Problem-Based Instruction: A Comparative Study of Instructional Methods and
Student Characteristics," Interdisciplinary Journal of Problem-based Learning,
1(2), 49-69.
Part A: Précis of the Article
Mergendoller et al. compared the effectiveness of an alternative pedagogical model known
as problem-based learning (PBL) with a traditional lecture-discussion model of instruction.
PBL inverts the traditional lecture-discussion (didactic) approach by beginning each
curricular unit of study by posing a problem to students that has been carefully designed by
course instructors (more often called facilitators) to simulate real-life problem scenarios and to
catalyze the acquisition of curricular knowledge, concepts, and principles. PBL is described as a
student-centered, collaborative, and inquiry-based pedagogy— teachers do not assign specific
learning activities, instead small-groups of students pursue their own solutions to these problems
by engaging in a delineated and guided inquiry process roughly in the form of: identifying the
problem, defining information pertinent to solving the problem, identifying the new knowledge
students need, learning the new knowledge and then applying it to solve the problem;
constructing a product that communicates their thinking and is evidence of their learning.
Facilitators usually guide students throughout the process by asking questions and providing
ongoing constructive feedback. Usually, they delay content lectures until students realize they
need to understand a concept (just-in-time delivery). (Woods, 2000, p. 2-1, 2-6)

2. Daniel Genesee Ero Siouga—SP10
Although PBL has been extensively studied in professional schools and undergraduate
programs, its value as a curricular approach in secondary schools has been less studied.
Researchers recruited 5 teachers from 4 different secondary schools in California. Each instructor
taught at least one class using a lecture-discussion approach and one class using a PBL approach.
All instructors received the same training in PBL methodology and were assessed to ensure that
PBL classes were conducted in a manner consistent with the approach. All instructors taught
macro-economics and all classes covered the same macro-economics content. Each teacher
selected which class would be PBL and which would be lecture-based, but they made this
choice before the start of the school year, and before they received any class-lists to minimize
selection biases. 346 twelfth grade students across 11 classes were enrolled in the study, but only
246 students completed the study—researchers attribute the high attrition rate to a common
phenomenon in the United States—grades in second semester of year 12 often do not count for
college admission, and so student attendance commonly drops off. Researchers noted that
absence rates were stable across school subjects in the schools they studied and so did not
attribute them to any effect of the studied variables.
Researchers selected 1) verbal-ability as a proxy for general academic ability and measured
it using a validated instrument called the Quick Word Test: Level 1. Researchers also studied 2)
students’ interest in learning economics by designing their own instrument (a questionnaire),
which attempted to assess interest without assuming basic knowledge of economics, to avoid
selecting students based on prior economic experience instead of interest alone. Similarly
researchers also developed a questionnaire to assess 3) preference for group work, and 4)
Student-perception of problem-solving ability. Macroeconomics knowledge was the fourth and
final outcome measured by researchers. Researchers assessed knowledge by administering the
same unit-specific content test across all study classes. The test used multiple-choice questions
from the Test of Economic Literacy. Questions were selected to represent the full-range of
Bloom’s taxonomy.
Although researchers assessed all four variables at the start of the study to ensure that
classes (PBL and didactic) did not differ significantly from each other in ways that might indicate
selection biases, only variables 1) and 4) were assessed as student-important outcomes and

3. Daniel Genesee Ero Siouga—SP10
measured post-test. It should be noted that some classes did differ from each other at baseline—
Teacher A’s traditional class and Teacher C’s PBL class had significantly higher verbal-ability than
their class-mates engaged in the contrasting approach. Also, Teacher D’s traditional class
perceived themselves to be better problem solvers—however researchers did not consider these
differences overly-problematic to the analysis.
Based on a survey of existing research focused on PBL and secondary schools, researchers
hypothesized that there would be no difference in knowledge-outcomes between students
enrolled in a PBL curriculum v. students in a traditional curriculum. However, their results
showed that for the whole study sample, as well as two of the five teachers, PBL students gained
significantly (p<0.5) more knowledge than the students in a traditional course. The effect size was
equivalent to a raw score difference of 4% in a percentile grading system. Although the gains in
knowledge for PBL students only reached significance for two teachers, PBL class gains were
greater than didactic gain for four of the five teachers. Traditional class gains outpaced PBL class
gains for only one teacher, Teacher C, though the difference was not statistically significant.
Researchers noted that Teacher C taught in the same school as another Teacher whose PBL class
gains were larger than their lecture-discussion class gains.
Researchers also hypothesized that there would be no difference in knowledge between
students with different verbal ability in didactic and PBL classes. They accepted this hypothesis,
but demonstrated that, while students with high verbal ability performed similarly (p>0.05) with
respect to knowledge-outcomes in either traditional and PBL-based classes, students with
midrange and lower verbal ability learned more in PBL classes (albeit not significantly more) than
traditional classes. The effect size corresponded to a raw score difference of 6-7% in a percentile
grading system.
Finally, researchers hypothesized that there would be no difference in macroeconomics
knowledge gains among students with different levels of subject interest, group-work preference,
and self-perceived problem-solving ability. Researchers ultimately rejected this hypothesis and
showed that students who expressed the highest interest in learning economics learned more in
PBL classrooms than peers in lecture-discussion based classrooms. The difference in measured
knowledge-outcomes between high-interest learners in PBL v. didactic classrooms was

4. Daniel Genesee Ero Siouga—SP10
equivalent to a raw score gain of 8% in a percentile grading system. There were no significant
differences between curriculum-approach groups with respect to group-work preference and
problem-solving efficacy.
Part B-Reaction of the Article
The latest revisions of nearly all Ontario Curriculum Outlines emphasize the development
of inquiry, problem-solving, and collaborative learning skills, and in some subject areas,
prioritize their development above basic conceptual disciplinary understandings where the
reverse was formerly true (Ontario Ministry of Education [OME], 2008). Given the emphasis on
inquiry, problem-solving and collaboration across the Ontario Curriculum, other alternate
pedagogical models, such as PBL, that more directly target the development of collaborative
inquiry problem-solving ability may be more appropriate to secondary school learning than the
traditional lecture-discussion method still commonly employed in secondary education.
PBL was developed at McMaster University, and was implemented as an alternative
instructional model for medical school. It has since been adopted in professional schools and
undergraduate programs around the world. Only recently, have educators made attempts at
implementing PBL at the elementary and secondary school levels. Though a significant body of
research exists, which examines the effectiveness of PBL post-secondary, there are fewer studies
that examine its utility in high school. Proponents argue that PBL better replicates how people
truly learn than didactic models of education—that embedding knowledge, old and new, in the
context of a problem helps people integrate that knowledge and generates more lasting learning.
They also argue that it is better at developing transferable skill sets, such as communication skills,
general problem-solving ability, and both collaborative and independent self-directed inquiry
skills. (Hmelo-Silver et al., 2006) Opponents generally argue that the cognitive demands of PBL
are simply too great for less experienced students, and that its usefulness, if any, is limited to
mature (i.e. undergraduate and/or professional) and highly-motivated/interested students with
strong academic ability. (Kirschner et al., 2006)
This study is interesting because it explores the merits of PBL in secondary education. It is
relatively well-designed. Researchers have gone to reasonable lengths to minimize the risk of

5. Daniel Genesee Ero Siouga—SP10
selection biases in their study: specifically, by looking at multiple teachers in multiple school
settings with differing socio-economic backgrounds; and also by performing base-line
comparative analyses to ensure classes did not differ from each other at baseline in ways that
could skew results. There were some significant baseline differences, but they were not overly
problematic for the final analysis because the groups that differed from each other, did so with
respect to verbal ability, which was not correlated with a significant difference in knowledge
outcomes for students between study groups by the end of the study.
The high attrition rate is unfortunate, since larger sample sizes lead to more
generalizability. However, since the drop-out rate is likely not attributable to the study design or
one of the class-conditions (PBL v. didactic) and the sample size is still fairly large and robust
(246 student across multiple school settings), the attrition does not significantly undermine the
integrity of the final study analysis. Therefore the study’s power remains fairly strong.
The study was was regionally confined to Northern California, which may limit its
generalizability to other geographic regions, if there are factors unique to Northern California
that support the effectiveness of PBL, I haven’t been able to anticipate what those theoretical
differences may be, but a larger study involving multiple teachers, in multiple schools across
multiple geographical regions would be the ideal next step. Alternatively, a study in Ontario
would obviously generate conclusions that are more generalizable to Ontario students.
It is particularly interesting that researchers rejected their second hypothesis, and showed
that PBL did not selectively favor students of any particular general academic ability (as
measured through verbal ability). In fact, the non-significant but relatively large (in terms of
effect-size) knowledge-outcome gains seen among learners with the highest and lowest-verbal
abilities, suggests that PBL may actually be helpful in closing the gap between students of lower-
academic ability and their higher-achieving peers, without interfering with the knowledge-gains
of the high-achievers. Hopefully a future study will examine PBL by deliberately creating groups
of mixed ability students so that this possible benefit of PBL can be further explored. Until then,
this study provides good evidence that PBL does not necessarily pose a problem to less
academically able students as some critics fear.

6. Daniel Genesee Ero Siouga—SP10
It is also interesting that according to the results of the study, PBL seems to more effectively
support the individual interests of students—i.e. students who expressed the highest interest in
learning economics learned more in PBL classrooms than high-interest peers in lecture-
discussion based classrooms. Researchers argued that one explanation for larger knowledge
gains in highly-interested students may have been that PBL allowed them to “capitalize on their
interest to expand their personal explorations of economics in the PBL
classrooms…”(Mergendoller, Maxwell, & Bellisimo, 2006, p. 63) more easily than they could in
a traditional classrooms with a more prescribed outline of course content. Students who
expressed the lowest interest in studying economics were at least no worse off than their low-
interest peers in didactic classrooms.
Similarly students who did not express a preference for group-work were not disadvantaged
in a PBL curriculum, despite small group work being a defining characteristic of the approach—
there was no significant difference between the knowledge gains made by students who
preferred group work and those who did.
I would like to end this reaction piece by noting that, within Toronto, there is at least one
publicly-funded alternative school that already bases its pedagogical approach in PBL—Delphi
Alternative School (DAS). It appears that at least some practicing Ontario educators are already
attempting to use PBL to meet Ontario Curriculum expectations. The results of this study support
their work and the general notion that the PBL may be an effective model for structuring
interaction among students that fosters shared learning, while also ensuring individual learning. It
also provides support for the evidence-based work of the many groups of researchers and
educators who developed PBL as a curriculum approach that reflects how people actually
develop and learn.

7. Daniel Genesee Ero Siouga—SP10
Bibliography
Delphi Secondary Alternative School (2012). Retrieved from http://schoolweb.tdsb.on.ca
Hmelo-Silver, C., Golan Duncan, R., and Chinn, C. (2006) Scaffolding and Achievement in
Problem-Based and Inquiry Learning: A Response to Kirschner, Sweller, and Clark,
Educational Psychologist, 42(2), 99-107
Kirschner, P., Sweller J., & Clark R. (2006): Why Minimal Guidance During Instruction Does Not
Work: An Analysis of the Failure of Constructivist, Discovery, Problem-Based, Experiential,
and Inquiry-Based Teaching, Educational Psychologist, 41(2), 75-86
Ontario Ministry of Education. (2008). The Revised Ontario Curriculum Grades 9 and 10:
Science. Retrieved from http://www.edu.gov.on.ca/eng/curriculum/secondary/
science910_2008.pdf
Woods, D. R. (2000). Problem-based learning: How to gain the most from PBL. Waterdown, Ont:
D.R. Woods