School history content in recent years has been shifting away from the "grand" story of history towards historical literacy, based on critical thinking and historical research skills. This encourages the explora-tion of the possibilities of developing these skills from primary school onwards, using a variety of ac-tive learning methods in social education classes. The aim of the study was to determine whether the targeted use of timeline tasks in the educational process can improve the historical time comprehension skills of third grade pupils in Lithuanian primary schools. The focus of the study was the use of timeline tasks in the understanding of historical time. The aim of the study was to explore the changes in the historical time comprehension skills of 3rd grade pupils in a primary school when timeline tasks are purposefully applied in the educational process. An action re-search study was carried out, 16 educational activities were organized in two primary school third grade classes. In one classroom, 8 activities involved the purposeful use of timeline tasks. Students' historical time comprehension skills in the category of timeline application were assessed through quantitative and qualitative content analysis of the questionnaires completed by students. It was found that before the educational activities, some of the pupils in grade 3 had not reached the level of devel-oping understanding of historical time at level A in the category of application of the timeline. A com-parative analysis of the data after the educational activities showed that the pupils in Class X who worked on the timeline tasks during the educational activities achieved higher results than their peers in Class Y who did not work on the timeline tasks during the educational activities. The results of the study suggest that the use of timeline activities in history learning enables students to better orient themselves in historical time and to achieve higher learning outcomes. Keywords: understanding historical time, timeline application, primary education, action research