Just go and ask if you can hang out with them at recess or something. I'm sure they won't refuse if they are old friends. Maybe bring something you can share, and offer them some of it.
Oh, sorry. Thought you said you were in middle school. Same applies, but during lunch period or spares. And if you don't have fixed seating in classes, just go ask if it's ok to sit beside them. But usually people will want to sit in the same places, so that will be tough. But if seating is changing often, then try doing that.
Also, just be friendly to everyone in class. Talk to whoever you sit beside, and offer help to people when you're done your work early.
Honey at your age, remember this....Friends come and go...however, Enemies accumulate....this is the natural flow of things...no news is good news...just pick up where you left off like nothing happened and all will be forgiven...savior the moment, don't sabotage the memory....
If they were your friends, just go over to them. In a few minutes you'll feel like they were never away.
Start talking to them and take it from there
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