Say the name out loud and you have the groove: boom · bap · boom-boom · bap. Kick on 1, snare on 2, kick on 3 and again on the & of 3, snare on 4. Exercise 2 is that bar note for note, and exercise 1 is the same bar with the extra kick removed. Play them back to back: one 8th note in the foot is all that separates a plain backbeat from golden-era hip-hop.
That one note does real work. Beat 2's snare stands alone with no kick near it, while beat 4's is set up by a kick an 8th note ahead of it, so the back half of the bar leans forward and the front half sits still. Everything else in exercises 1, 2 and 4 stays plain: straight 8ths on the closed hi-hat, nothing shorter than an 8th note, no crash, no toms, no fills. Boom-bap gives you almost nothing to hide behind.
Six snare notes, only two of them loud
Exercise 3 is where the groove starts to breathe. The hi-hat doubles to 16ths and runs all sixteen of them, and the snare now appears six times: the a of 1, 2, the & of 2, the e of 3, the a of 3, and 4. Only 2 and 4 are backbeats; the other four are ghost notes at roughly a quarter of that volume. The staff accents the two backbeats and leaves the four ghosts plain, so you can see the shape, and the Play button sounds it: the two backbeats come out at full volume and the four ghosts at a quarter of it. Hearing that ratio is the easy half; producing it from one hand at two stick heights is the lesson.
Snare and hat land together on back-to-back 16ths, so the hat line cannot be shared: the right hand carries all sixteen, and the left hand supplies every snare note, loud and soft. Two things will fight you. The a before each backbeat gives the left hand two consecutive 16ths, quiet then loud, into 2 and again into 4; let the quiet one creep up and the ear hears two hits of equal weight, which blurs where the backbeat is. Beat 3 then alternates foot and left hand under the running hat: kick, ghost, kick, ghost, which puts the second half of the boom-boom on the & of 3 between the two ghost notes. Learn the snare voice alone against the click before adding the hat; one-handed 16ths at ♩ = 88 are their own piece of work.
Dragging the snare without dragging the hat
Exercise 4 drops the ghost notes and returns to exercise 2's bar, deliberately: only one variable changes. Lock the hi-hat and the kick to the metronome, then place the snares on 2 and 4 late. That is the laid-back feel, and it is the whole assignment. Not late by a rounding error, though. At ♩ = 88 a 16th note runs about 170 milliseconds, and the drag you want is roughly a fifth of that, near 30 milliseconds: small on paper, unmistakable to the ear. Hat and snare are notated together on 2 and 4, so they stop landing as one attack — hat first, snare a hair behind, about the width of a flam. That gap is the sound.
The failure is always the same. The hands follow the snare, the hi-hat sags to meet it, the next bar starts a shade late, and thirty seconds later you are playing ♩ = 85 and calling it feel. Laid-back and slow are different things, and the metronome is the referee. Loop exercise 4 for two minutes and grade the hi-hat, not the snare: if the hat is still nailed to the click at the end, the drag was real. When it sags, play exercise 2 square for a minute to reset. The next lesson rejoins the drag to the ghost notes, where the whole snare voice moves late as one instrument.