Need advice on approaching classmates

So, my science class has 5 juniors (including me) and the rest are seniors. 3 of the other juniors have kind of grouped together (not previously knowing each other) so I’m left with the last who is always high and stuff, and gets suspended a lot. How do I easily approach the other juniors in my class and so I can be with them for assignments rather than the one who is always stoned? Thank you in advance!