The study of the subject is of distinct importance for the pedagogical practice of the Portuguese language teaching. Many issues have been raised about the inadequacy of the definitions applied to the examples and exercises in grammars. In this dissertation, we present a review of these definitions, stablishing comparisons among the examples given in traditional grammars, teaching materials and sentences that appear in the non-pattern use of the language. Our theoretical framework is based on the functionalist approach, in which we have chosen the valency grammar which classifies the grammatical subject as a complement and the systemic grammar of M.A. K. Halliday which presents the subject performing papers defined by the verbs. Based on the issues raised and based on the analysis of the definitions we are convinced that that model which the traditional practice has established as the model for the teaching of syntatic analysis must be re-evaluated, since we have noticed many serious contradictions between the theory and the practice.