First principles thinking (or reasoning from first principles) is a way of thinking and problem-solving that breaks down a complex problem into its most basic assumptions, facts, concepts, or ideas to gain new knowledge and find new solutions through reassembling them from the bottom-up. There were attempts to introduce this way of thinking into engineering education in recent years . Problem-based learning, a student-centered approach in which students learn a subject by working in groups to solve an open-ended problem, offers great platforms for utilizing first principles thinking in deepening their learning and producing solutions. Here we reported the elaborate design of two PBL projects to facilitate the students´ learning by practicing first priciples thinking in two PBL small student groups. The aim of the design was to enable students to develop the first principles thinking by deconstructing problembased learning projects to their fundamental concepts and rebuilding their solutions from the ground.