Some educative softwares have offered tasks that already are carried through normally in a classroom, but they use, in the maximum, computational features that magnify the motivation of the learning. Others, instruction softwares, do not allow the pupil to try situations and to participate in a more involving way. The use of the computer in the education, however, is justified when softwares are used to allow the apprentice to carry through activities which are difficult to be implemented in an environment without the computer. The importance of a survey of the more recent pedagogical studies of the subject that will be approached by the software is basic, since the methodologies to teach a content change with time, and constantly researchers discover new approaches to facilitate its learning. In this study, the research of the involved pedagogy in the education of fractions, together with the analysis of the approaches of several educative softwares, have allowed the elaboration of a prototype: a computational environment to assist the learning of fractions. This subject was chosen because presents innumerable difficulties in the teach-learning process, mainly for the lack of adequate resources that allow the pupil to explore with few limits the involved concepts, principles and relations in the representations and operations of fractionary numbers. It is distinguished as result the importance that must be conferred to three strategies of interaction pupil-software, in an approach in relation to the constructionist paradigm: (i) Construction - it allows the pupil to construct directly from its actions, having an objective to be reached. The pupil can manipulate the fractions represented by bars, through diverse tools, as cutting pieces, dividing a bar, putting a bar into motion, comparing sizes, etc. (ii) Simulation - it allows the pupil to try its hypotheses, to test them, to analyze the results and, through experimentations, to discover existing relations between the action and the final result, and still the chance of being able to perceive and to surpass the error, as far as the environment does not say anything regarding its error or rightness. The fractions can be represented graphically or symbolically, and the environment makes the other simulated representation. The solution itself is not so important as much as the process to arrive in itself. (iii) Microworld - from a small set of easily manipulable primitive the pupil constructs innumerable domains. Through the many available tools in software, together with the pre-formed ideas of the concrete objects that are supplied, as the "bar", the pupil constructs the fraction concept, as well as the understanding of its basic operations (equivalence, matching, add, subtraction, multiplication and division). For example, through the tool "undo/redo" other paths are tried to solve the same problem, developing the metacognitive task and emphasizing the process for the solution in detriment of the isolated solution. The presented environment breaks with inherent limitations to the manipulation of materials used normally in the learning of fractions, complementing the lessons that contain difficult situations to be dealt by the teacher. It also offers the understanding of the more complicated concepts, as well as the multiplication and division operations, and allows to develop a work in group with great benefits, due to the discussion among pupils and teacher, that makes the necessary complementations to the learning and still guides the group to follow an appropriate route, in order to get a more significant learning.