The melody of Rock Around The Clock by Bill Haley & His Comets runs 142 notes across 19 bars, 0:49 long in A at 180 beats per minute. The tab sits almost entirely in the first two frets, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? Rock Around The Clock chords and lyrics.