Reading is an often overlooked aspect of drumset playing. There are those of us who studied formally and were trained to read, and there are those of us who are "self-taught" or learned to play by jamming along to records, or whatever.
I am here to tell you that even though I grew up playing in original bands 90% of all of my gigs nowadays require reading. If you want to do session work, if you want to be a freelance hired gun, if you want to do Broadway shows, if you want to be a top call player in your scene, you have to be able to read.
The exercises in this section take simple rhythmic phrases and give you a solid workout on not only getting the reading part happening but also coordinating some various ostinato patterns on top of the reading to totally solidify the who thing.