This experimental study is trying to verify the basic hypothesis, that laboratory-based courses play an important role in a development of key competencies in science and technologies, namely in promoting better conceptual understanding, better communication skills and better professional skills of learners. We focused on the evaluation of the efficiency of different types of nowadays e-labs, using Ma and Nickerson (2006) four-dimensional educational goal model. We found slightly different patterns and enlarged the model to five dimensions: (1) design skills, (2) conceptual understanding (3) social skills (including teamwork and networking) and professional skills (4) inquiry planning and (5) data processing. We tried to specify clearly the differences, advantages and disadvantages of all three kinds of e-labs according to educational goals to be achieved. In the second part of the study, we focused on investigating (not verifying) the hypothesis, that it is not only the actual nature of the laboratory, but the beliefs that students and teachers have about it which may determine the effectiveness of developing key competencies.