Line two 18x13" rimmed baking sheets with parchment paper. Lightly flour work surface with bread flour and turn Master Dough out onto surface. Using a chef’s knife or bench scraper, divide dough into eight pieces (about 90 g each). Working one at a time, pull edges of portioned dough up and over into center, then turn over, seam side down, onto a less-floured spot (you want the dough to have friction with the surface). Cup your hand around dough and, working your hand in a circular motion, draw dough across surface to create a ball.
→ Need help shaping? This video from King Arthur Flour will show you how.