With the application of a panel model, comparison tests of means and structural breaks, the impact that the loss of classroom hours has had on the results obtained by the students of the José Miguel Carrera National Institute in the Selection Test University was evaluated, as a consequence of the student mobilizations that began in 2006. The evidence shows a systematic deterioration of the scores obtained by the students from 2011 as a result of the accumulated loss of face-to-face classes, however this decline is not proportional to the number of hours lost, a situation that reflects structural problems in the José Miguel Carrera National Institute related to the effectiveness of the use of school time.