Your going to love this site. Probably will learn more here then your class. At the least be able to throw some curve balls at the instructor.
20yrs of electrical experience plus reading here has yielded more knowledge than most going to school. They paid $20k for school and some can barely wire a thermostat. It's 5 wires on most systems (standard 4, plus common). It surprises me how many newbies aren't able to find the common in the furnace/air handler on the older hard wired systems. Most of them get it when I tell them to find the condenser wire, but some don't.