Out of necessity, we created a new protocol called the Classroom Observation Protocol for Undergraduate STEM, or COPUS. Like the TDOP, this new protocol documents classroom behaviors in 2-min intervals throughout the duration of the class session, does not require observers to make judgments of teaching quality, and produces clear graphical results. However, COPUS is different in that it is limited to 25 codes in only two categories (“What the students are doing” and “What the instructor is doing”) and can be reliably used by university faculty with only 1.5 hours of training (Figure 1 has a description of the codes; the Supplemental Material includes the full protocol and coding sheet). Observers who range from STEM faculty members without a background in science education research to K–12 STEM teachers have reliably used this protocol to document instruction in undergraduate science, math, and engineering classrooms. Taken together, their results show the broad usability of COPUS.