This text focuses on phonological variables in continuous speech and writing. I examine only the realization or cancellation of segments fixes syllabic in medial and final word in Portuguese. The research follows the theoretical and methodological bases of Change Theory with emphasis on Educational Sociolinguistics. It has the goal of demonstrating that the novices in literacy process often have difficulties in written segments performed variably in speech, especially when it comes to change in progress. There is a comparison between boys and girls at school. These results confirm that women present more prestigious standard forms, according to other studies in the area. They refer also to the independent of variables as (a) the size of the lexical item, (b) previous segment, (c) the grammatical category of the word. The extension shows greater effect on the cancellation of the segments, a fact related to language processing whose guiding principle prove the tendency of larger segments, heavier, more prone to cancellation-fixes operation. The study is aimed ultimately provide effective teaching methods to deal with the influence of speech in writing in literacy, pointing that guidance addressed is positive if is based in academic research.