I would consider STEM to consist of two dimensions: understanding the natural world and finding solutions to solve problem in the world
The understanding part concerns knowledge in Science and Mathematics, both disciplines are fundamental to our quest to know what this world is all about and why/how things happen in nature. Contrary to what many would think, Science isn’t always about doing experiments and getting our hands wet in the laboratory, although a good part of it is, and that part is essential to help us demonstrate certain phenomena and prove certain hypotheses — some of the greatest scientists have spent all their lives describing and proving theories using a chalk and the blackboard (check out Einstein’s work, for example). In the short series, Genius on National Geographic (first season), Einstein is said to value doing science much more than engineering by discouraging his son from reading engineering in the university.