The current study addresses the limited research on knowledge acquisition in Project-Based Learning (PjBL) and assesses its development using a Multidimensional Curriculum Model (MdCM) among 563 elementary and secondary school students in Israel. The mixed-method approach involves a quantitative pre-post design, comparing intervention groups who are studying modules based on MdCM to control groups using traditional PjBL. The knowledge measured comprises three dimensions: declarative, procedural, and conditional. Qualitative measures, including semi-structured interviews and reflective diaries, added information on student learning. Main findings indicated an effect of MdCM as a form of PjBL which showed significant differences between intervention and control groups in terms of total knowledge acquisition, particularly in procedural and conditional knowledge. Interviews and reflective diaries elaborated on the significant link between thinking processes and knowledge acquisition, indicating that students perceived development of their cognitive abilities and personal competencies. In this study, implications for teaching using MdCM as a novel PjBL approach are discussed.