“See one, do one, teach one” is a saying of medical training. A trainee watches a procedure once, performs it once, and then teaches it to the next trainee. Sources credit the model to William Halsted, the first surgeon-in-chief of Johns Hopkins and founder of its surgical residency program. No source found shows that Halsted used the words himself.
A 2022 journal article notes that the “do one” step “has become less acceptable due to concerns regarding patient safety.”