This study is an investigation of assessment and learning in the curriculum area of mathematics based on the current practices of a State government primary school. A case study approach provided a rich source of information on a means of measuring change over four years of schooling (Year 3 to Year 6). The learning was focussed on student knowledge, in relation to the mathematical tests selected as measurement tools in this study. A learning continuum developed was for students involved in the investigation and the opinions of their parents and teachers and selves sought via surveys. Designs selected that prevented disruption to the normal operation of the school at the centre of the investigation. The literature of Izard, Black and William, Forster and Broadfoot guided the educational context of the investigation into formal assessment practices for formative purposes. Modern Rasch analysis computer developments enabled the exploration of Rasch analysis techniques offering the researcher access to statistical information previously confined to statisticians and contributing to the investigation of effect size and the work of Cohen, Glass and Coe in measuring the magnitude of change. Sampling and analysis methods relating to validity and equating procedures supporting comparison issues required investigation and application. The disadvantages of decisions made outside and without consideration of teacher and students investigated with particular reference to the impact these decisions can make in relation to student learning.