In this article, I discuss a case of pre-primary and primary school teacher education concerning place value in number representation. In primary school (in Italy, in grades 1 and 2), the topic is usually introduced by means of manipulatives (for instance, abaci and base ten blocks). But it is well known that no artefact is transparent for mathematical meaning, unless the social practices of the mathematics classroom, initiated by the teacher, are effective. The aim of this study is to report on tasks given in a four-session (16 h) workshop for 27 prospective pre-primary and primary school teachers, where the use of artefacts in learning place value in base ten was tackled, within a suitable theoretical framework. Different sessions of the workshop are analysed, focusing on tasks related to different components of mathematics knowledge for teaching. Effectiveness for professional growth is reported, quoting documents written by students and by external evaluators. In a final paragraph, the implication for pre-primary school teacher education is addressed.