As a result of the COVID-19 pandemic, many instructors were forced to adjust from in-person to emergency remote teaching; however, classroom observation protocols, like the Classroom Observation Protocol for Undergraduate STEM (COPUS), have only been developed and validated for in-person instruction. Therefore, we developed and validated an adapted version of COPUS, called Online COPUS (O-COPUS), to measure teaching and learning practices during online synchronous instruction. We collected COPUS and O-COPUS data from 35 STEM instructors teaching via in-person and online synchronous instruction at a research-intensive, minority-serving institution (MSI). By identifying emergent codes from live observations and using an exploratory coding process, we adjusted six instructor and six student COPUS code descriptions for O-COPUS. As we prepare forteaching in the future, it is important to have formative assessment tools, like classroom observation protocols, designed for all course formats to be able to measure and improve pedagogical practices in college STEM classrooms.