For 4-year-olds
By four, the question shifts from what to why. Children want to know what holds a plane up, whether they could build something that flies, and what happens when it does not work the first time. Episodes that let a character try, fail, adjust and try again match this exactly, and a first flight told as a real event, packing, waiting, taking off, gives a four-year-old something to rehearse in play. Look for stories that treat the wobble before take-off as normal rather than something to be talked out of.