The study investigates project-based learning (PBL) in Spanish secondary education, motivated by the 2007 economic crisis and the subsequent need for economic literacy among students. PBL, unlike traditional methods, reverses the learning order: students acquire knowledge while solving a problem. This approach promotes problem-solving skills, collaboration, and critical thinking. However, the effective implementation of PBL requires careful consideration of both cooperative learning and innovative evaluation systems. The research aims to understand how cooperative work functions within PBL and how the evaluation process unfolds from both the teacher's and student's perspectives.

The literature review examines existing research on project-based learning and cooperative learning. Several authors highlight the importance of collaboration and the challenges of managing group dynamics, such as the 'stowaway effect' (students not contributing fairly) and intragroup conflicts stemming from differing capabilities or communication issues. The review also discusses the need for formative assessment methods that go beyond traditional evaluations, emphasizing student involvement in the assessment process through self and peer evaluation. The importance of teacher's role as guides and facilitators in managing both cooperation and evaluation is also discussed.

This qualitative case study involved 16 fourth-year secondary education students (8 female, 8 male) and 5 teachers (3 male, 2 female) at Cristo Rey Polytechnic Institute in Valladolid, Spain. The students participated in an economics project, "My Business Plan." Data collection involved teacher interviews, teacher reflective diaries, and student open-ended questionnaires. Data analysis employed ATLAS.ti software, using both inductive and deductive coding cycles to identify themes. The researchers engaged in a rigorous process of inter-rater reliability checks and triangulation of data from the different sources to ensure credibility and validity. The saturation point in data analysis was determined when comparisons no longer revealed new insights.

The analysis yielded 41 explanatory codes grouped into four categories: learning, interaction-collaboration, motivation, and organization. Analysis of teacher interviews and reflective diaries highlighted the use of small, heterogeneous groups to facilitate collaboration and communication. However, teachers also acknowledged significant intragroup friction and conflicts stemming from unequal contributions among students. Student questionnaires echoed these concerns, with students expressing frustration over uneven workloads and unfair grading practices. In terms of evaluation, while teachers valued formative assessment methods such as self and peer evaluation, the reliance on traditional testing remained prominent. Students also indicated a lack of teacher follow-up on the project process, leading to concerns about the fairness of the final group grade.

The findings indicate that while PBL can be effective in promoting student engagement and developing key skills, careful attention to group dynamics and evaluation methods is crucial. The prevalence of intragroup conflicts highlights the need for explicit teacher guidance and support in managing cooperative learning. The continued emphasis on traditional evaluation methods, despite awareness of the benefits of formative assessment, points to a potential disconnect between theory and practice. The study suggests a need for more robust teacher training in facilitating collaborative learning and implementing diverse, student-centered assessment practices.

This study underscores the potential of PBL but also its challenges. Effective PBL requires proactive teacher intervention to address group conflicts and ensure equitable participation. A shift towards more comprehensive and formative evaluation methods that integrate student self and peer assessment is essential. Future research could explore the effectiveness of specific interventions to improve group dynamics and evaluation strategies within PBL contexts.

The study's limitations include its small sample size and its focus on a single school. The findings may not be generalizable to other contexts. Furthermore, the qualitative nature of the study limits the ability to make quantitative claims about the effectiveness of PBL.