In this work, a specific implementation of a so-called experimental or open-ended laboratory is proposed and evaluated. Keeping in mind the scheduling limitations imposed by the context, first-year engineering physics laboratory practices have been revised in order to facilitate acquisition of the skills that are required in the experimental work. These skills concern different conceptual and procedural abilities related to designing experiments, taking measurements, analyzing the results and reporting properly the whole process. The employed approach is described, and the achieved results are evaluated by a series of tests at the beginning and end of the academic year. Additionally, the students' laboratory reports are used to quantify the evolution of acquiring these scientific skills. The evaluation of the results obtained from the aforementioned tests and laboratory reports gives enlightening information about students' apprehension of the experimental method itself, as well as the difficulties they find in each of the different, complex tasks that they must carry out during this process.