The article is based on the upper secondary school theme, the Development of the Slovene nation in the 20th century, and tries to illustrate the teaching of key events in the 1980s by using historical sources. In parallel, we wish to provoke the development of critical thinking by including some assignments containing critical thinking elements, such as finding and evaluating sources, separating facts from opinions, deductive reasoning, evaluating and decision-making. The historical explanation of events contains the main political and social processes which took place in the 1980s. The content of assignments is based on culture and economy, which are otherwise sometimes left out of school lessons, but have, nevertheless, a significant impact on the changed perspective that resulted in the massive support for Slovene independence at the end of the 1980s