Advanced instruction are courses that build on prior knowledge (and therefore have prerequisites).
Advanced skills are ones that depend on prior proficiency in other skills to be usable.
One example of this is math.
Counting is basic (or is it).
Addition and subtraction build on counting and are, in comparison, advanced.
Multiplication and division build on addition and subtraction and are, in comparison, advanced.
Algebra builds on multiplication and division and is, in comparison, advanced.
Yet, algebra is considered one of the basics for more advanced subjects involving the understanding of a wide range of subjects, including finance, business administration, all the engineering disciplines, and even the physics of ballistic flight.
I'm not even going to start talking about trigonometry, calculus, etc. etc.