Think of two or three informal groups that you are currently a part of or have been in the past

3 answers

Hmm -- let's see -- there were
my single friends with whom I went to Europe
another group with whom I went dancing on Friday nights

Oh -- wait!

Your teacher doesn't want my groups. Your teacher wants YOUR groups.
You have never had regular playmates, a group you sit with every day for lunch at school, or some other group you hang with? A circle of friends you do things with? Even an on-line gaming group?
How about your social media "friends"? Do they make an informal group?