In 2014, the Finnish National Board of Education launched a new core curriculum with the aim of meeting the skills and competence requirements of the 21st century. The purpose of this case study was to find out what transversal competencies Finnish eighth graders developed and how they experienced studying in a problem-based transdisciplinary course, which was arranged for the transitional stage between the former and the new curriculum. The qualitative data consisted of questionnaires and interviews. The analysis followed the methods of qualitative content analysis. When asked about their learning, the students commented on not having learnt much, referring to the discipline-based knowledge. Instead, they had learnt skills through teamwork, problem solving, and expression of their views and opinions, an aspect that they did not clearly connect with the things to be learnt at school. Many students felt that they acquired the competencies that they would need later in their lives. The students' teamwork had a crucial impact on their learning experience. The timeframe for the integrative approach needs careful consideration; the learning process in this course was perceived as being successful because it was long enough. Our study highlights that focusing on students' views is critical when reforming curriculum.