Learning by Design (LBD) is a project-based inquiry approach for interdisciplinary teaching that uses design contexts to learn skills and conceptual knowledge. Research around the year 2000 showed that LBD students achieved high skill performances but disappointing conceptual learning gains. A series of exploratory studies, previous to the study in this paper, indicated how to enhance concept learning. Small-scale tested modifications, based on explicit teaching and scaffolding, were promising and revealed improved conceptual learning gains. The pretest-posttest design study discussed in this paper confirms this improvement quantitatively by comparing the conceptual learning gains for students exposed to the modified approach (n = 110) and traditional approach (n = 77). Further modifications, which resulted in a remodified approach tested with 127 students, show a further improvement through reduced fragmentation of the task and addressed science. Overall, the remodified approach (FITS model: Focus - Investigation - Technological design - Synergy) enriches technology education by stimulating an empirical and conceptual way of creating design solutions.