Research in the Didactics of Science has often been characterized by a focus on specific didactic lines. Each line articulates its own theoretical foundations, objectives, and methodologies; however, they share a common goal: to understand and improve the processes of teaching and learning science. Among these lines, studies on misconceptions, critical thinking, and problem-based learning are particularly noteworthy. Consequently, studies that integrate multiple lines are relatively rare, yet they represent a promising area for further exploration.

With this purpose in mind, an exploratory study was conducted involving 16 students from a 6th-grade class in a Portuguese state school. The aim was to assess the effectiveness of a set of three activities, designed according to the principles of Problem-Based Learning (PBL), in promoting both knowledge construction and the deconstruction of scientific misconceptions regarding the cardiovascular, urinary, and reproductive systems. PBL is based on the presentation of a real-world problem, the resolution of which should hold personal, social, and/or environmental relevance for the student. It employs an inquiry-based approach to the teaching–learning process, aiming to foster critical and logical thinking skills. It also enables students to engage in autonomous work, while promoting collaboration through small-group activities and social interaction during the presentation of their work. Throughout the PBL activities, the teacher acts as a facilitator or mediator of learning.

More specifically, two objectives were defined:
(i) to evaluate whether the activities promote autonomous knowledge construction and their effectiveness in students’ performance on questions with varying levels of conceptual demand, particularly in understanding and application;
(ii) to analyse the impact of these activities on the deconstruction of misconceptions.

The study employed both quantitative and qualitative data collection methods, including direct observation using performance assessment grids (evaluating autonomy, engagement/participation, interest and respect for others, and final presentation), learning assessment worksheets, and a final opinion questionnaire about the activities.
The study results demonstrate that the integration of the two didactic lines led to overall positive outcomes, albeit with moderate impact. Students showed progress in autonomy, interest, and respect for others from the first to the third activity. Engagement and participation were highest during the second activity. In the final presentations of their work, students performed better during the second activity and showed improvement in presentation management, which stabilized by the third. Learning assessment results were positive across the studied dimensions, with marked improvement in the second activity—possibly due to the nature of its content. Thus, students were able to perform well on both comprehension and application questions and managed to deconstruct some of the misconceptions they previously held. It is also worth noting that the students were accustomed to a more traditional teaching, which may explain some of the difficulties they experienced in adapting to a more autonomous, student-centred methodology.

Questionnaire responses indicated that most students found the activities helpful for autonomous knowledge construction and for challenging and overcoming misconceptions about the human body systems addressed.

Keywords: Primary Education, Problem Based Learning, Misconceptions.