i befriended people from all my classes
if they sit next to you then its peak opportunity, most friends are made this way
now introduce yourself when teacher gives you time, or when you have to do team assignments. finish quickly while talking a bit with them. if you have time after submitting talk more. over time build up the talking, compare classes. what makes strong friends is if you see each other more often, although not necessary. the friends that pop up to my mind first, i had for 4 periods together
however you can find that some friends will be superficial
like the zesty guy who chooses female friends over you and talks shit behind everyone's backs
its trial and error
but you will find diamonds amongst coal