I thought that when kids learn how to ride a bike they can (1) use those "small" wheels on both sides that allow them not to fall and learn how to balance.. or

I thought that when kids learn how to ride a bike they can (1) use those "small" wheels on both sides that allow them not to fall and learn how to balance.. or (2) their parent puts a metal bar behind the seat and uses it to help keep the kid in balance: when the kid falls too much in some direction the parent uses the bar to push the bike back. After some time the kid learns how to balance on their own. As for other stuff, simulators?