A mobile material screening apparatus (100) for separating bulk particulate material into groups of particles of differing sizes comprises a support chassis (2), a horizontal screen box (3) housed within the support chassis (2) and an additional inclined pre-screening module (50) which is adapted to be demountably attached to the support chassis (2). The mobile screening apparatus (100) comprises five outputs. Foldable conveyors (7a, 8, 9, 910, 920) can be deployed outwardly from and stowed inwardly against the material screening apparatus. The provision of an inclined pre-screening module (50) provides relief to the horizontal screen box (3) by first removing the larger sized particles from the bulk material which can be returned to a crusher for recycling and serves also to increase the total number of grades of material separated by the screening apparatus.