1 PROBLEM-BASED AND LECTURE-BASED LEARNING: A QUASI-EXPERIMENTAL STUDY WITH NATURAL SCIENCES STUDENTS Clara Vasconcelos 1 and Joana Torres 1 1 Geology Centre/ Faculty of Sciences, University of Porto, Porto Portugal Abstract: Problem-based learning consists of a student-centred learning methodology that develops diverse skills, critical thinking, scientific reasoning and knowledge, decision-making, assessment and self-evaluation. The present research aimed to compare problem-based learning and lecture-based learning regarding the acquisition of scientific knowledge. The study followed a quasi-experimental research methodology with a non-random selection of participants. The study was undertaken with natural science students during the first trimester of the 2012/2013 school year. Results show that, in cognitive terms, students showed improvements that, although more positive in the experimental group of problem-based learning, did not prove to be more significant than those achieved with the lecture-based learning. However, the relevance of the study consisted on the demonstration that the introduction of a new methodology in the teaching of natural sciences (in this particular case the problem-based learning) did not cause any decline in academic success (it was as successful as the lecture-based learning) but rather potentiated the development of other competences directed to the scientific processes and research capabilities. Keywords: problem-based learning; lecture-based learning; quasi-experimental study; natural science students INTRODUCTION The introduction of new teaching methodologies in the classroom has always been a matter of controversy (Carrio et al., 2011), especially due to the inevitable fears of failure. The concern with the length of programs and preparing students for national exams often overlaps any attempts to improve learning by changing the teaching process. Competences development is often overlapped by the acquisition of knowledge, in order to ensure school achievements in standardized exams. Nevertheless, the lack of competences development reveals itself in the long term, particularly through the inability to mobilize knowledge and apply it to new situations. As such, ensuring school success in natural sciences goes far beyond the quantitative results achieved in national tests and calls for the learning of other skills, for instance, scientific reasoning, self-regulation and autonomy in the learning process (Almeida & Vasconcelos, 2012). The data herein presented comprises 115 students from middle-school, and stems from a project that researches the contribution of problem-based learning in science education for citizenship. The main goal of this study was to explore whether or not problembased learning (PBL) could guarantee cognitive gains in natural science students, especially when compared with lecture-based learning (LBL). Ultimately, the study intended to verify whether the PBL was at least as effective as LBL in helping students
2 to achieve the knowledge required to fulfill the natural science syllabus learning objectives. RATIONALE Problem-based learning is recognized as an inquiry approach because it prompts student s curiosity to solve problems, but also since questioning and research are at the core of the development of the process of learning. Furthermore, an inquiry approach also relates to activities in which students develop knowledge and the understanding of scientific ideas, as well as catch on how scientists study the natural world (NRC, 2008). PBL consists of a student-centred learning methodology that starts off by addressing a real-world problem, and whose resolution is deemed to be personally, socially and environmentally important. After creating an invitational scenario that presents the problem (Torres et al., 2013), the teacher has to foster students during the investigation helping them to became a more self-directed learner (Barrel, 2007).This methodology requires a shift in the educational paradigm, as students become active constructers of their knowledge and the role of the teacher shifts from presenter of information to facilitator of a problem-solving process (Allen et al., 2011). This methodology is characterized by students working in small groups so as to improve knowledge construction and to develop different competences (Wong & Day, 2009). Although it is difficult to implement collaborative work, this methodology also presents advantages since it allows both students to share points of view and teachers to better guide the development of the different tasks. The more or less well-structured problems (scenarios) act as a stimulus for the students learning processes (Wong & Day, 2009). This PBL scenario should motivate students to raise issues and look for solutions through inquiry activities. Although the PBL process calls on students to become self-directed learners, teachers must guide them by monitoring discussion, asking questions and fostering participation (Allen et al., 2011). One of the barriers that arise in the use of PBL is the lack of teachers qualified to play the role of facilitators and mediate the process (Hmelo-Silver, 2004). Moreover, most students evaluations do not contemplate teamwork or the collaboration developed with PBL (Savin-Baden, 2004), rather considering only the more conceptual issues. This methodology aims to develop communication skills, critical thinking, scientific reasoning and knowledge, decision-making, assessment and self-evaluation. These competences are considered to be essential for a lifelong learning process (Vasconcelos, 2012). However, whenever a new teaching methodology is implemented within science classrooms, many doubts and criticisms arise from school directors, some teachers, students and even parents. Several studies have already provided some experimental evidence that backs the assumption that the PBL methodology does not affect the students factual knowledge acquisition when compared with more traditional LBL (Carrió et al., 2011). Other studies suggest that PBL is significant to the development of generic and scientific skills since students are faced with complex problems and have to look for solutions creatively (Carrió et al., 2011) and also because PBL develops skills that are often ignored in middle science classrooms (Hmelo-Silver, 2004; Wong & Day, 2009). Even in medical education, where PBL has been largely applied and investigated, design-based research is still needed to enrich our understanding of the nature of PBL (Dolmans et al, 2005).
3 Within this framework, our claim follows the majority of studies related to this learning method (and to how students learn by using it) when unanimously presenting some cautionary notes, and suggesting that careful research is needed so as to understand if and how its potentials might be achieved. METHODS The study followed a quasi-experimental research methodology with a non-random selection of participants. Two groups were defined (an experimental and a control group) and a cognitive test, specifically built for this purpose, was applied in both phases of the intervention (pre-test and post-test). The aim was to investigate whether the PBL promoted larger cognitive gains that the LBL had done. The sample integrated students of natural sciences from two classes of two public schools in the north of Portugal. The convenience sample was constituted by 115 students: 64 integrated the experimental group and had a 12.1 age average, and 51 integrated the control group and had a 12.5 age average. The teacher of the experimental group was familiar with the PBL methodology and knew how to play the tutor role during the research intervention. The sample was mostly female: the experimental group consisted of 30 boys and 34 girls and the control group integrated 21 boys and 30 girls. The intervention programme was aligned with the Portuguese natural science curriculum. One problematic scenario was presented related to fossils and their significance for the reconstruction of earth history. Later on, questioning was promoted and the students sought for the solution with the help of teacher mediation. The research involved practical work (fossilization modelling) that was carried out by the students, and potentiated learning processes, research capabilities and scientific reasoning. Students were assisted in the process of learning cognitive knowledge enclosed in the curriculum, focussing on memorization, understanding and mobilization of knowledge to new problem situations. Accordingly, after the research students were challenged with an activity that demanded for the application of the knowledge and the skills that had been developed, thereby allowing for the re-conceptualisations and the consolidation of the learning objectives. The cognitive test was applied before the teachers intervention (pre-test) and after the implementation of the geological scenarios (post-test). The application of each test lasted 45 minutes. Students were made aware of its non-assessment character as well of the need to carefully think on the answers. The scenario was applied during the first trimester of the 2012/2013 school year and the intervention took place during three 45 minutes classes. Students were given the necessary sources for research. As recommended by PBL, students worked collaboratively, in groups of 4 to 5 elements, and were mediated by the tutor. RESULTS The sample was analysed before the implementation of the intervention, through the calculation of the averages obtained in the cognitive pre-test and the significance of differences between the value of the control group and the experimental group. The objective was to perceive whether the academic results of the students, evaluated in
4 cognitive terms by the cognitive test, would be similar in both groups. They are listed in Table 1. The averages obtained by the cognitive pre-test were higher in the experimental group (20.1 versus 15.7) with a higher standard deviation in the control group (9.88 versus 9, 59). The Mann-Whitney test showed a statistically significant difference in these groups very early in the intervention (U = , p <0.05), and the experimental group presented the best performance. Nonetheless, there were several reasons encouraging us to proceed with the study: (i) the difficulty in getting teachers and students to voluntarily participate in educational studies, and the possibility that relevant data could emerge in the questionnaires to be applied after the intervention; (ii) the fact that the research team had an ethically commitment to help teachers to learn and to apply the methodology of PBL; (iii) the fact that the literature emphasizes the cognitive gains resulting from PBL, and as such the experimental group could significantly exceed the value obtained on the pre-test average in relation to the control group. Table 1 Cognitive pre-test results. pre-test experimental group control group average 20,1 15,7 standard deviation 9,59 9,88 minimum 0,00 0,00 maximum 43,00 47 After the intervention, the Cognitive Test was applied again, in the natural sciences class. Results are shown in Table 2. Table 2 Cognitive post-test results. post-test experimental group control group average 41,2 33,3 standard deviation 19,11 15,69 minimum 15,00 8,00 maximum 84,00 69,00
5 The post-test average is higher in the experimental group, although both groups show poor ratings. The Mann-Whitney test resulted in a statistically significant difference between these groups after application of geological scenarios (U = , p <0.05), showing that the cognitive improvements after the intervention again define groups with distinct levels of success, the experimental group achieving the best outcome. The Wilcoxon test was used to verify whether the average difference of the pre and post cognitive test, for each of the groups, was statistically significant. The experimental group showed an improvement of the average in the cognitive test, increasing from 20.1 to The difference that was obtained was statistically significant (Z = , p <0.05). For the control group, the average obtained at the cognitive pre-test was 15.7 and at the post-test was The difference that was obtained was also statistically significant (Z = , p <0.05). DISCUSSION AND CONCLUSION Considering the main objective of this study, which consisted in analysing the benefits of using PBL, we notice that students showed improvements in cognitive terms. Although these were more positive in the experimental group of PBL, they did not prove to be more significant than the results achieved with the LBL. The relevance of the results arises, nonetheless, since we found that students also have academic success with PBL. This work has proven that the introduction of this new teaching methodology (in the midst of an educational system characterized by a predominantly traditional one), did not cause a drop in knowledge acquisition. Notice that this concern is cause for criticism, confusion and conflict between teachers whenever one wants to implement new teaching methodologies. The present study has demonstrated that such concerns are groundless students not only maintained (or increased slightly) the cognitive gains as they had the opportunity to research and perform tasks that benefit the development of scientific reasoning. Such an opportunity would never have been offered by LBL, since lectures and the reading of textbooks appeals only to mechanical memorization and the rhetorical reproduction of school contents. Despite the methodological advantages of PBL, the weak acquaintance of students with the process hindered the classroom dynamics, thus demanding for a wider and more frequent resort to PBL in science classes, so as to reassert its educational potential. Other studies can and should also be developed so as to verify if PBL promotes knowledge retainment to a larger extend than more traditional methodologies, both in PBL targeted students and in students subjected to the LBL. As a result, more evidence will back and sustain the advantages of favouring of PBL. ACKNOWLEDGEMENTS This research was carried out within the scope of the Research Project Science Education for Citizenship Through Problem-Based Learning (PTDC/CPECED/108197/2008), funded by FCT within the scope of the Thematic Operational Program for Competitiveness Factors (COMPETE) of the European Union Community Support Framework III co-funded by the European Regional Development Fund (ERDF/FEDER).
6 REFERENCES Allen, D. E., Donham, R. S. & Bernhardt, S. A. (2011). Problem-based learning. New Directions for Teaching and Learning, 128, Barrel, J. (2007). Problem-Based Learning: An inquiry approach. Thousand Oaks: Corwin Press. Carrió, M., Larramona, P., Baños, J.E. & Pérez. J. (2011). The effectiveness of the hybrid problem-based learning approach in the teaching of biology: a comparison with lecture-based learning. Journal of Biological Education, 45 (4), Dolmans, Diana H J M; De Grave, Willem; Wolfhagen Ineke H A P & Vleuten Cees, P M van der (2005). Problem-based learning: future challenges for educational practice and research. Medical Education, 39 (7), Hmelo-Silver, C. E. (2004). Problem-Based Leaning: What and How do Students Learn? Educational Psychology Review, 16 (3), National Research Council (2008). Inquiry and the National Science Education Standars: A guide for teaching and learning. Washington: National Academic Press. Savin-Baden, M. (2004). Understanding the impact of assessment on students in Problem-Based Learning. Innovations in Education and Teaching International, 41 (2), Torres, J., Preto, C. & Vasconcelos, C. (2013). PBL Environmental Scenarios: An Analysis of Science Students and Teachers Questioning. Journal of Science Education, 14 (2), Vasconcelos, C. (2012). Teaching Environmental Education through PBL: Evaluation of a Teaching Intervention Program. Research in Science Education, 42 (2), Vasconcelos, C. & Almeida, A. (2012). Aprendizagem Baseada na Resolução de Problemas: Propostas de trabalho para Ciências Naturais, Biologia e Geologia. Porto: Porto Editora. Wong, K. K. H. & Day, J. R. (2009). A Comparative Study of Problem-Based and Lecture-Based Learning in Junior Secondary School Science. Research in Science Education, 39,