Facebook Group

I started a nifty little group on facebook a while back to keep track of friends who went to my Chinese School. I checked on it recently and there's three people from CUNY Brooklyn and Stuyvensant. My question is - did they actually go to my Chinese School (and if so, why on earth would anyone want to travel so far for a Saturday morning class?) or did they just randomly decide to join? (and if so, should I try to kick them out of the group...?)