Under the empiricist theory of language acquisition known as Usage-based Model it is assumed that the process of acquisition is gradual, from concrete to abstract; infants’ representation of grammatical knowledge is considered to be "acquired" in bottom-up fashion. This view is compatible with recent, that is, non-traditional, theories of machine learning such as connectionist models, and therefore it can be said to have a plausibility at least from a computational point of view. At the same time, however, descriptive plausibility should be achieved. In this study, an innovative method called History-Sensitive Description (HSD) is presented in order to describe the development in the usage-based fashion. This method utilizes the history of the utterances by one infant to describe the current knowledge state of the infant. HSD gives us a set of representation at any moment of development if a longitudinal data is given.