This work presents the results of two-year-long pedagogical research, the aim of which was to demonstrate the applicability of the usage of a new strategy in education--Integrated e-Learning (INTe-L)--through its introduction into project-based physics teaching in Slovakia. The INTe-L strategy is built around the role of experiments and interactive simulations in knowledge acquisition and on the possibility of integrating scientific methods in education. The elements of INTe-L are the following: (a) real on-site and real remote experiments, (b) interactive virtual experiments (e-simulations) and (c) educational e-materials. The primary objective of our study was to determine the suitability of project-based teaching with INTe-L elements for the topic "Energy Sources". The research was based on the following hypothesis: project-based teaching via INTe-L of the topic "Energy Sources" in physics is more effective than the traditional (instructionist) way of teaching. To verify the hypothesis, we performed a pedagogical experiment on a sample of 155 respondents in the 9th grade at two primary schools in Slovakia. The pupils were divided into two working groups: an experimental group (EG) of 85 pupils and a control group (CG) of 70 pupils. The pupils with worse grades were included in the EG. To get relevant feedback, pre-test and post-test studies and an interview were developed and applied. The results attained in both groups were statistically processed, evaluated and subsequently compared. A two-phase test with dispersion equality proved that differences in the pre-test scores in the EG and CG were not statistically significant. The differences in the final didactic test (post-test) results achieved by the EG and CG, on the other hand, were statistically significant and better scores in the EG were obtained. A positive change of pupils' attitude in the EG towards physics after the execution of our project-based teaching was noted. The evaluation of the results attained by the pupils proved that the introduction of project-based teaching via INTe-L was an effective strategy to improve Physics teaching. As such, the implementation of this interactive strategy into the instructional education process at primary schools is recommended.