The purpose of this article is to examine history classroom interactions in Chilean secondary schools in relation to the transmission of historical memories of human rights violations committed by Augusto Pinochet’s dictatorship from 1973 to 1990. Corpora of this research are comprised of history lessons filmed in the two types of public schools that coexist in the Chilean educational system, namely government subsidized and partially subsidized schools. This research draws on linguistics resources framed by the sociosemiotic perspective of systemic functional linguistics. We incorporate into this theoretical framework the notions of semantic gravity and semantic density from legitimation code theory in order to understand the variations of levels of specialization and abstraction that build cumulative knowledge and ideological cosmologies when one is dealing with a sensitive and complex aspect of Chilean society.