OK. Texas found a site where he thought he could get a straight and honest answer. No need to beat him up if you think it is a bogus question. This really should be a place where there is no stupid question.
Texas -
TBS is not basic flight school. There is a TBS forum here where you can get lots of info on what TBS is.
Flight school consists of a number of different phases, each of which will have different size classes. After TBS you will go to API in Pensacola. I think class sizes there average around 30 students. Then you will go to Primary. Class sizes in Primary are typically 12-20 students, depending on where you go (Whiting, Corpus, Vance) and when you start. Advanced flight training classes vary in size a great deal. Could be 2. Could be 20. Depends, again, on where you go and when you start.