So something like an A/B schedule? 
You have 8 classes total, but only go to 4 each day.
EX:
C1, C2, C3, and C4 are A days
C5, C6, C7, and C8 are B days

Week one is A/B/A/B/A
Weeks two is B/A/B/A/B
*Repeat etc

Like that?

Or just literally only 4 classes a semester/every 7 weeks?