In preschool and primary school pupils differ in many respects, including the capacity to self-regulate their playing and learning processes. Relative autonomy or self-regulation in development, and relatively high attainment usually co-vary already before a pupil starts preschool. However, at preschool entrance, development and educational processes are usually adapted to the mean levels of the pupils in the playing group or class. A theoretical framework is sketched in which pedagogical-didactical and organisational conditions support diagnostically based playing and learning processes for each pupil in a preschool group or primary class. ICT characteristics to further support differentiated playing and learning processes are specified as well as possibilities to develop playing and learning in optimal ways for both pupils and school. One of these possibilities concerns self-regulation of a pupil in the group or class context, which is most important for the pupils achieving highest in cognitive areas. An experimental study is being carried out in 10 preschools and primary schools to develop and realise the pedagogical-didactical and organisational conditions, ICT support, and procedures to make playing and learning optimal. The results reveal some important characteristics of school innovation processes that may block or promote improvement processes in educational practice.