There are several forms of instructors working together. There are the multiple section model where multiple instructors are teaching in-sync across multiple sections, sometimes using a common syllabus and common assessments. That is a good topic, but not this one. This co-teaching note is about when two or more instructors work together on the same course!
Based on observations, there are three possible outcomes: it goes great, kinda neutral ho-hum, or it goes south, chalk and cheese, oil and water, pure oxygen and a lit match.
Instructors have to be compatible to make it work, respect each other's expertise for "their parts" of the course. Sharing means helping the other instructor (and them helping you) to both make the workload for instructors manageable and to support student learning. It is more than just dividing up the time if course components have to come together.
Possibly related situations would be a professor who is working with a lab instructor who is handling that part of the course. This is different than the traditional instructor <--> TA relationship, and also different than two instructors working together as peers because there is a power dynamic.
This note describes how to make things smooth and how to leverage each instructor’s contribution and potential.
