The purpose of this article is to describe and analyze a teaching experience on pronoun placement in two groups of 3rd year of high school. The experience was guided by the concepts of Teaching Sequence (Dolz, Noverraz, Schneuwly, 2004), Language Analysis (Kemiac and Lino de Araujo, 2010) and linguistic variation (Patriot, 2009, and Bagno, 2013). This experience focuses on the teaching of linguistic usage analysis of cases of enclisis, proclisis and mesoclisis, in many situations use; for this, the notion ofTS was reviewed and, based on Cunha (2012), it is understood as a set of organized activities to achieve a learning goal. The data analyzed stem from the ongoing evaluation of the SD, which led to the redirection of planning. The results indicate that the initial and final simulated were not the best indicators of learning. An activity of fixation made on the sixth module of SD presented the most reliable indicators of learning. Thus the conclusion is that diagnostics can not function as good indicators for the evaluation of a SD.