The opposite of "true" is not always "false". Sometimes, the opposite of one kind of truth is truth of a different kind, most clearly seen in the difference between literal and metaphoric truth. Fairy tales dwell in the latter world; they are true but unreal. To children, this distinction is important and they need no help in understanding it, although this is a complex idea.
Many adults know the situation, when they are telling (not reading) a story of the fairy-tale kind and the child interrupts to ask: "Is it true?" (If the adult is reading, it is clear to the child that it is from the story world and they don't ask.)
Is it true? the adult wonders, thinking about his goblin neighbors, troll boss, and the princess he has been secretly in love with for years, and answers thoughtfully, "Well, yes, it is true, in a way. In its own way it is true."
"But is it true like in real life?" the child persists.
"No," the adult will say, the distinction clear. "Not like in real life."
The child's question is not one of disbelief, but rather comes from the important need to clarify what kind of truth it is and therefore what kind of belief to give to it.
-Jay Griffiths, A Country Called Childhood: Children and the Exuberant World