A vibratory screening machine, comprising: an outer frame; an inner frame connected to the outer frame, wherein the inner frame includes one or more securing mechanisms; a vibratory motor assembly attached to the inner frame such that the vibratory motor assembly vibrates the inner frame; and a plurality of replaceable screen deck assemblies, each screen deck assembly comprising a first screening deck configured to receive a first screen assembly and a second screening deck configured to receive a second screen assembly, wherein the first and second screen assemblies (409, 419) are secured to the first and second screening decks (410, 420), respectively, by tensioning the screen assemblies (409, 419) in a direction that a material to be screened flows across the screen assemblies (409, 419), wherein each screen deck assembly is secured within the vibratory screening machine in a stacked position within a stacked configuration of the plurality of screen deck assemblies and wherein at least one of the plurality of screen deck assemblies is configured to be attached via the one or more securing mechanisms to the inner frame, and wherein each screen deck assembly comprises a first screen tensioning system configured to tension the first screen assembly and a second screen tensioning system configured to tension the second screen assembly; an undersized material discharge assembly configured to receive materials that pass through the screen assemblies (409, 419), wherein the undersized material discharge assembly includes an undersized chute in communication with each one of the plurality of screen deck assemblies; and an oversized material discharge assembly configured to receive materials that pass over a top surface of the screen assemblies (409, 419), wherein the oversized material discharge assembly includes an oversized chute assembly in communication with each one of the plurality of screen deck assemblies. an outer frame; an inner frame connected to the outer frame, wherein the inner frame includes one or more securing mechanisms; a vibratory motor assembly attached to the inner frame such that the vibratory motor assembly vibrates the inner frame; and a plurality of replaceable screen deck assemblies, each screen deck assembly comprising a first screening deck configured to receive a first screen assembly and a second screening deck configured to receive a second screen assembly, wherein the first and second screen assemblies (409, 419) are secured to the first and second screening decks (410, 420), respectively, by tensioning the screen assemblies (409, 419) in a direction that a material to be screened flows across the screen assemblies (409, 419), wherein each screen deck assembly is secured within the vibratory screening machine in a stacked position within a stacked configuration of the plurality of screen deck assemblies and wherein at least one of the plurality of screen deck assemblies is configured to be attached via the one or more securing mechanisms to the inner frame, and wherein each screen deck assembly comprises a first screen tensioning system configured to tension the first screen assembly and a second screen tensioning system configured to tension the second screen assembly; an undersized material discharge assembly configured to receive materials that pass through the screen assemblies (409, 419), wherein the undersized material discharge assembly includes an undersized chute in communication with each one of the plurality of screen deck assemblies; and an oversized material discharge assembly configured to receive materials that pass over a top surface of the screen assemblies (409, 419), wherein the oversized material discharge assembly includes an oversized chute assembly in communication with each one of the plurality of screen deck assemblies.