The main objective of this study is the design and validation of an educational methodological model based on the use of immersive technological resources (Augmented Reality -- AR) to improve learning processes in secondary education science subjects (Biology and Geology). The process was developed based on three main quantitative studies: an exploratory study, a study of performance divided into three cases studies, and an attitudinal study. The information obtained was completed with a fourth qualitative study of the training of teachers who participate in educational technology. This research provides empirical evidence that allows validation of the methodological model developed to explain key concepts and to improve the level of motivation and acceptance of AR technology by students. The proposed model can induce improvements in educational processes in the field of STEAM when used with an immersive AR technological resource and an adapted digital evaluation system. It also demonstrates that teachers require specific training in connection with the creation and the adequate use of AR educational resources, and of digital evaluation systems as well. The results of this study have important implications for the field of education, demonstrating the potential of AR technology to improve learning outcomes and the need for teacher training in its use.