Inside the walls of East High School, there are only two things that really matter: basketball and the dulcet tones of musical theater.  This was the world the Disney Channel Original Movie High School Musical dropped waiting preteens into when it debuted on Jan. 20, 2006. Twenty years later, High School Musical and the subsequent two films stand as  one of the most impactful series ever created by the children’s channel — not only setting records for DCOMs, as their devoted fans call them, but