Purpose: This study aims to identify critical online teaching effectiveness factors from instructors' perspectives and experiences during COVID-19. Design/methodology/approach: This study used a qualitative phenomenology approach. In addition, the research used a snowball sample to identify faculty in the engineering and engineering technology fields with experience in online teaching and learning. All interviews were conducted online by the researchers. The interview questions were based on findings in the current literature. Further, the questions were open-ended. Findings: The analysis identified eight major themes that impact online teaching effectiveness--class recordings; course organization; collaboration; engagement; exam, assignment and quiz grades; games; valuable course content; and student timely feedback and response. Research limitations/implications: The study was not designed to be generalizable to the entire population of professors who teach online classes but to gain insights from faculty who taught online courses during the COVID-19 pandemic. Practical implications: Faculty can use the factors identified for online teaching effectiveness to enhance their course design and delivery while teaching online or blended courses. Originality/value: This research provides insights into factors that impact online teaching effectiveness during the COVID-19 pandemic.