Science, technology and engineering functional literacy should be developed purposely in the school system -- like any other competence, it does not develop spontaneously. For this purpose, a didactic model, the Metacognitive Model for Developing Science, Technology and Engineering Literacy (McM_T&E), was developed. Apart from acquiring knowledge and skills from the field of technology and engineering, the McM_T&E is equally focused on developing functional literacy in the field of technology and engineering, as well as in the field of science, through the development of students' metacognitive knowledge about reading strategies for reading STE explicatory texts and for reading manufacturing instructions. The McM_T&E was implemented in a Technology and Technique' (T&T) class, grade six, in Slovenia. Results show that focusing on science, technology and engineering literacy in Technology and Engineering classes by using the McM_T&E model increases the students' science, technology, and engineering functional literacy, which is a fundamental competence in the 21st century.