SO … When we go into a station, please fall into STATION FORMATION.

Do it automatically so Drill Sergeant Helen (aka LeatherLungs) won’t have to "PROJECT HER VOICE" (that's Japanese for "scream at us")

Basically, it just means get in line.
One of the teacher-types, usually me, will lead.
One will "ride sweep". They’ll walk behind everyone and make sure nobody gets left behind.
(Unless you’ve annoyed them. Word to the wise, eh?)

Another hint: Helen has knee problems and really REALLY appreciates it if someone carries her suitcase up and down stairs at the station.

Everyone else should keep up with the leader but don't get ahead.
Make sure not to get behind the "sweep"
Stick close together.
No more than two abreast if it gets crowded.