How do infant day care centers put kids to sleep?

Don't know about baby centres at large but where my baby used to go, the caretaker would pat the kids to sleep. Initially, when my kid took time to adjust, the caretaker used to carry him in her arms and would walk to and fro in the room till the time he would go to sleep. Caretakers in baby centres are trained professional and they know how to soothe babies.