There is a micro-phenomenon of new wave, special snowflake directors that try to revolution the canons of classical opera. I saw Carmen being banged behind a burning car next to what looked like a flamenco-infused Thunderdome. That was in Paris opera, stronghold of modernist SJW nonsense.
Here, the expression is a shorter version of matriculation college. In a number of Canadian cities, many government-run secondary schools are called collegiates or collegiate institutes (C.I.), a complicated form of the word college which avoids the usual post-secondary connotation.
STEM is an acronym that stands for science, technology, engineering and mathematics. STEM majors are an area of concern for the United States government, because not enough students entering college are going into STEM degree areas -- nor are there enough STEM teachers and other professionals in this area.