This study explores Science, Technology, Engineering and Mathematics (STEM) teachers’ perceptions of teaching and assessment methods. We investigated 125 STEM subject coordinators and teachers using interviews and questionnaires. We examined the most commonly implemented teaching and assessment methods, and the reasons teachers chose them. Then, we compared teachers from different school levels, subjects, teaching experience and cultural backgrounds. The teaching methods implemented the most were lectures and presentations, followed by class discussions and collaborative classwork. The most implemented assessment method was tests with open- and closed-ended questions, followed by project portfolios and experiment reports. Subject coordinators preferred methods that integrate formative assessment more than teachers. The study contributes to a better understanding of the teaching and assessment methods implemented in schools and the gap between recommendations and actual implementation. Conducted prior to the COVID-19 pandemic, this research sets a baseline for similar future post-COVID research.