Technological pedagogical content knowledge (TPACK) is important for teaching science during the COVID-19 pandemic. This paper investigates the TPACK of Finnish and Thai primary school teachers in the context of teaching science through blended learning (BL) during the COVID-19. 11 teachers from Finland and Thailand were interviewed. The interview data were examined using deductive content analysis. The analysis revealed that all teachers used educational technology in their online classes in terms of providing the lesson content, learning activities, and the students’ learning assessment. Zoom and MS Teams were the tools used for online teaching in both countries. The main teaching method used in both types of instruction was experimentation. For online instruction, most teachers considered educational technology in every step of the teaching process to enhance students’ learning of science as much as possible. Many types of direct and technology-mediated interaction appeared during BL, especially during online teaching, which could be designed and analyzed in the context of the TPACK model.