Abstract: A disc screen classifies material by size. The disc screen includes a frame, a plurality of shafts mounted on the frame parallel with one another and a first stage including discs mounted on the shafts in a substantially coplanar row. Each of the discs has a perimeter shaped to maintain the space between discs substantially constant during rotation. A second stage includes discs mounted on the shafts in a substantially coplanar row. Each of the discs has a perimeter shaped to maintain the space between discs substantially constant during rotation. A receiving section agitates debris while the debris moves at an angle up to a given elevation. A roll over section drops the materials down to a discharge position for feeding onto a discharge section. The materials are dropped from the roll over so that the debris either falls vertically or flips over further promoting separation. The discharge section again agitates the debris while moves up a second incline until the larger debris discharges out a rear end.