Visually discriminating upper case letters, lower case letters and numbers.

English and number literacy are important for successful learning and testing student literacy and numeracy standards enables early identification and remediation of children who have difficulty. Rasch measures were created with the RUMM2020 computer program for the perceptual constructs of visual discrimination upper case letters, lower case letters and numbers. Thirty items for Visual Discrimination of Upper Case Letters (VDUCL), 36 for Lower Case Letters (VDLCL) and 20 for Visual Discrimination of Numbers (VDN) were presented to 324 Pre-Primary through Year 4 children, aged 4-9 years old. All students attended school in Perth, Western Australia. Eighteen of the initial 30 items for VDUCL, thirty-one of the original 36 items for VDLCL and thirteen of the original 20 items for VDN were used to create linear scales (the others were deleted due to misfit) and these clearly showed which letters and numbers children said were easy and which were hard.