Research shows that teachers are one of the most influential factors in student learning in online classrooms during the COVID-19 pandemic and discusses teachers' efforts to get the most out of their online classrooms with their students. However, how the teachers experience online teaching is understudied. To address this concern, this case study aimed at revealing the experiences of primary school teachers in online teaching during the COVID-19 pandemic with a particular focus on the difficulty in teaching different subjects such as mathematics and science. The participants were 12 primary school teachers working in different places (e.g., village and district) with various professional experiences in years (such as 1-10 years and 11-20 years). The data was generated through semi-structured interviews and analyzed by content analysis. The results revealed four main themes, namely guidance and support, planning and instruction, technical issues, and the use of technological tools. Since most of the results were contextual, it is suggested that schools provide some school-based training to support teachers and parents in this process. When the results of the research are evaluated, it is important that university teacher education departments provide comprehensive pedagogical support, especially for pre-service teachers who will be the teachers of the future and families to improve online learning.