This study shows the way in which sustainable learning through cooperation with parents is achieved before, during and after the lockdown period (COVID19) by applying systematic formative assessment. Therefore, as a result of this cooperation, through the planning and realization of the formative assessment, students' motivation is achieved, and this positively affects their sustainable learning. The study has a research character and points out the impact of feedback on student achievement from the perspective of parents and teachers. The study analysis is based on the quantitative data collected through a survey with parents (N = 21), qualitative data collected by the teacher through planning and implementation of the formative assessment and cooperation with parents through written comments. Based on the results of the findings, it is concluded that through timely interventions by teachers and cooperation with parents, gaps can be filled in, so that the children are informed appropriately and a real, reliable and systematic assessment is carried by the teachers.