Their isn`t really a certain type of underwear that all girls wear when they get to high school,
every girl has her preferences.
I personally wear thongs every day with the exception of when i`m on my period.
I don`t wear them to be slutty,
I wear them because whenever i`m wearing a dress or sweat pants or something similar other types of underwear show panty lines which I find embarrising.
I will admit that they also make me feel a bit sexy and more mature,
but I don`t go around parading my thong or acting slutty with it.
I also know that lots of girls say thongs are uncomfortable,
but for me once I had been wearing them for about a week or two they actually felt more comfortable than other types of underwear I owned and that`s why I have switched to wearing thongs all the time.
I do know that other types of underwear shuch as bikini panties and boy shorts are also popular choices with girls in their teenage years,
but you need to wear whatever you feel the most comfortable with.