I'm not Navy either, but I've been reading . . .
The platoon is the group of plebes your kid will be with this summer.
The Company is the basic group for the Academic Year. (made up of 2 platoons this summer).
The Battalion is a group of 5 companies. Companies 1 through 5 make up Battalion 1, and so forth.
The Regiment is made up of 3 battalions.
The Brigade is the whole student body.
I'm sure someone will correct me if I have gone awry.
Janet
Almost right.
Plebe Summer:
1 Regiment
2 Battalions (Starboard and Port)
15 Companies (Alpha through Papa, excluding Juliet)
30 Platoons
Once the Ac Year starts it transitions into this:
1 Brigade
2 Regiments (1st = Batt. 1,2,3; 2nd = Batt. 4,5,6)
6 Battalions (1st = Co. 1-5, etc.)
30 Companies
3 Platoons (w/ 3-4 squads)
Going into plebe summer, if your son/daughter got into, say, N-25 as his/her company, then they will be in 25th Company, 5th Battalion, 2nd Regiment during the Ac Year. Whereas, their sister company (N-26) who was with them through Plebe Summer will be 26th Company, 6th Battalion, 2nd Regiment.