Our conceptions of mathematics and of ourselves as researchers, teacher educators, teachers and students have been transformed as a result of school mathematical activity being viewed through international comparative filters. This paper depicts a model of school-centred teacher education that has been introduced to meet the new demands being placed on teacher knowledge and practice. This model provides an example of how changing practices impact on the social construction of mathematics itself. The paper concludes that the fields of psychology and mathematics each describe realities that are consequential to past human endeavours or conceptualisations. Neither of these fields depict stable truths.