Bargaining - S5-E21
Continuity mistake: When Juanita rushes down the stairs and goes outside the door, you can see that Gaby is holding a plate of leftover food in her left hand, but in the next shot the plate has suddenly changed into a bowl.
Bargaining - S5-E21
Continuity mistake: During the breakfast scene with Mike, Katherine and MJ at the start of the episode, the spoon in MJ's bowl of oatmeal changes position between shots.
Answer: Kayla was sent away in episode 16 (The Gun Song) in season 4, after falsely accusing Lynette of child abuse. She now lives with her grandparents - probably Nora's parents.
I'm curious why we never see her again, why she never talked about, and why Tom never mentions visiting her.