At the end of the 1970s, Bloom elaborated the well-known Model of School Learning (1976) with the aim of drawing up a scientific procedure for studying the possibility, through numerous researches at micro-level as well as large scale longitudinal studies at macro-level, of using individualised teaching methods to modify aspects which, according to traditional pedagogical theory, were considered innate and, therefore, impervious to change. The goal of this research was to focus attention on learning conditions and on the quality of the teaching in order to offer all pupils the opportunity to reach the results aimed for by the teaching project and maximise their potential. Bloom considered four factors affecting each pupil’s learning performance: family background, the level and kind of cognitive ability at the beginning of the teaching-learning process, the affective factors and the time taken by each pupil in the execution of a piece of work (time on task)1. This final variable was first analysed in depth by Carroll (1963) and later by Block (1972) and Anderson (1976); the main conclusion drawn from these works was that the time needed for a pupil to complete a task is variable. If, in fact, pupils are offered the help and the time needed to learn, then they not only become able but also manage to achieve the desired results in ever-shorter time spans. The research work of Bloom (1993), moreover, estimated the incidence and interaction of the three variables that the author considered sufficient to explain the learning results of any student, two of which refer to the learner while the third concerns the kind of teaching, i.e., the required knowledge and ability of each pupil, affective factors at the outset of the learning process, and finally the quality of the teaching: