Coming Home - S4-E1
Visible crew/equipment: In the very beginning, when Joey and Pacey are on the boat Coming Home, there are a few closeups of Pacey that show a small microphone jutting out the material of his shirt, right under his collar. (00:01:05)
Coming Home - S4-E1
Visible crew/equipment: In the scene where Joey and Pacey have arrived back at Capeside, and are getting things ready to get off the "True Love," in one shot you can see the microphone clipped to the back of Joey's shorts.
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.