This Paper describes how, based on a symbiosis of American and European thinking, "conceptual" labs for engineering courses have been developed in a series of design-based research projects that started in 1995. Researchers working in engineering education have been encouraged to "look for opportunities to translate research questions, theories, methods, and findings... across national and institutional boundaries", and urged to "think globally about the development of engineering education as a research field". Nevertheless, engineering education has been criticized for being insufficiently global in its practices. The aim of this paper is to meet these challenges. At first the design of labs was inspired by "interactive engagement" curricula such as "RealTime Physics" and "Workshop Physics" developed in the US, after they had been adapted to the Swedish setting and traditions. Variation theory, pragmatic and (post)phenomenological theories of the philosophy of technology, and activity theory influenced later development. Labs for advanced mechanics, and for introductory and advanced courses in electric circuit theory, were later developed using similar ideas. The labs utilized probeware and real-time computer-based measurement technologies as a mediating technology, and tasks were designed according to variation theory. Students learning in several designs of these labs has been studied by recording students activities and interactions by video, and using concept inventories such as the Force and Motion Conceptual Evaluation (FMCE). Some designs resulted in high achievement (normalized gains of 50-60%) on the conceptual tests, well in line with the results from the US. Furthermore, in the labs that led to high achievement, the technology was used help students to focus on important relationships and concepts, i.e. the technology functioned as a "cognitive tool". However, the implementation of probeware technology could also result poor achievement. This is explained by differences in how the tasks are designed and structured in the labs - the necessary patterns of variance and invariance in line with variation theory were missing. These results that identify important factors in students learning in labs differ to some extent from earlier proposals put forward to explain the success of interactive engagement curricula. The results also question some of the assumptions behind "active learning". The analysis presented in this paper was brought forth and facilitated by achieving synergies between American and European thinking.