Propaedeutic is a noun that refers to a preparatory study or instruction. 

Derived from the Greek word propaideuein (pro pie DEH oo een) which means ‘to teach beforehand,’ our word of the day has been used by English speakers since the mid-17th century. Here’s an example of it in use:

My history as a college student was pretty mixed. When I didn’t prepare, I got awful grades. But when I spent a great deal of time on a propaedeutic, I got slightly less awful grades.