100 Light Years From Home - S5-E19
Trivia: When Joey and Dawson are talking before they leave on their respective trips, Joey makes a comment about getting it right "in another life when we are both cats". This line was also made famous by Penelope Cruz in the movie "Vanilla Sky", starring her and Tom Cruise. Ironically, Katie Holmes is now married to Tom Cruise; and in the beginning of the Vanilla Sky movie when he is running through Times Square he goes by a large poster of none other than Katie Holmes. Bit of a coincidence? (00:03:00)
Trivia: During Pacey's 'Urban Legend'; the Diner Owner named Vic is Richard Fullerton, the same Actor who played the Prison Guard when Joey went to see her Father during the first season.
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.