It’s only semi-related to Common Core. Rather, it’s a loose grouping that the National Science Foundation came up with a few years ago to improve US competitiveness internationally.
It’s a bit of a misnomer, because only the natural sciences are included; rather misleading really.
So it’s primarily political really. Thankfully kids are generally smarter than that. My nephew, who is 10 years old now, was very clear that he got 3rd place an Engineering competition in the 4th grade and not a STEM competition, [even though all the literature said, “STEM” on it.]
Consider they’re immersed in the cruddy learning process, they’re able to more easily see the clear difference between Science, Technology, Engineering and Mathematics but the lines get blurred for those of us who are long out of school.