Answer:
Maybe u could say Lisa has decided to buy flowers for her friend's birthday. she recalled that her friend once told her about a flower shop that she likes alot. she decided to go to her friend's favourite shop. in order to get there, she rode a train. while buying, she fell down. a stranger helped her up. Lisa continue her journey
one day, during a lesson, the teacher announce that there will be a new student joining them and coincidentally, it was that stranger... and then they become friends :)