Say sorry and help him/her up.
Say sorry and walk off.
Say sorry pat him/her on the head and walk off.
Just walk past like it didn't really happen.
Ask them quietly to stop.
Yell, YOU BRAT! STOP THAT AT ONCE!
Yell at them to stop.
Don't do any thing, it's the teachers resposibility.
Help her with her groceries, then go home and make her a batch of cookies.
Help her with her groceries and then do nothing.
Go home and tell mom to help her.
Just walk past like she wasn't there.