With the research discussed here I aimed to examine the effect of the COVID-19 pandemic on primary school mathematics teaching processes and specifically the teaching process of 1st-grade geometric shapes. A holistic multiple case study design was used in this qualitative research. The participants were primary school teachers who have taught both processes and geometric shapes in 1st grade primary school and were selected using purposive sampling. Semi-structured interviews based on an interview form developed by me was used as data collection instrument. In this form, questions about the 4 skills in the programme related to geometry were included. Lesson content, materials, and content related to the method of expression related to each skill were examined comparatively during and before the COVID-19 pandemic. Semi-structured interviews during which the questions on the form were asked, were conducted with participating teachers. The content analysis technique was used to analyse the obtained data. The results of the analysis show that the transition to online education during the COVID-19 pandemic had serious consequences. Positive and negative effects were found in both primary school mathematics teaching process and the teaching process of geometric shapes in the 1st grade.