Final answer:
The scheduling method in which patients sign in and are seen on a first-come, first-served basis is called Open hours.
Step-by-step explanation:
The scheduling method in which patients sign in and are seen on a first-come, first-served basis is called Open hours. In this scheduling method, patients do not have a pre-scheduled appointment and are served in the order they arrive at the healthcare facility. It is a common practice in walk-in clinics and urgent care centers.