Literacy, in particular functional literacy in various fields and especially in the field of STEM, is becoming an increasing problem in modern-day society. The question arises, can the school system develop the kind of functional literacy in students, which allows them to fulfil, in real life, their personal and professional needs related to the competence of reading and creating written texts from the field of science, technology and engineering? The present research aimed to explore how students in today's schools are trained in functional literacy, especially in the fields of technology and engineering, and what kind of literacies in the field of STEM they are able to (or should be able to) master competently. The present research showed that students achieve relatively poor results in the area of functional literacy, both regarding their science literacy, and especially their technology and engineering literacy, which is a result of a lack of competence on behalf of mother-tongue teachers to develop this kind of functional literacy. Functional literacy should be developed by teachers of individual areas of STEM subjects.