Love Bites - S6-E18
Plot hole: At the end of the episode, Joey takes a taxi from Boston to Eddie's house in Worcestor. As she walks up to the front door, the cab leaves. Eddie has no idea Joey is coming, and she has no way to return to Boston without using a cab or asking Eddie for a ride. But she doesn't even know yet if Eddie is home, and whether he would offer to drive her home. Seems illogical for Joey to dismiss the cab without asking the cab driver to wait a few moments while she sees if Eddie is home, and if he would be willing to drive her back to Boston. Otherwise, she would have to ask his parents to use the phone to call another cab. (00:38:45)
Answer: It's only explained once in the series. Jack says to Andie "I tried to start kindergarten without you", meaning Andie was smart enough to start school early.