The thrill of teaching a child to spell.
Children figure out how to spell. They are the primary drivers of their learning. Children make tons of guesses about everything – what letters are, what spelling is, how to spell particular words, why to spell, how organize all the information to remember it, what parent/teacher is trying to say. Children think of tons of criticism of all their guesses and judge which ones are correct and which aren't. With lots of work, children figure it out.
Parents/teachers are helpers who play a secondary role. You cannot literally share ideas with someone. All you can do is make sounds, make gestures, write things down, draw pictures, etc. All you can do is create physical stuff (e.g. sound waves going towards child, patterns of photons with certain frequencies going towards child, or an arrangement of labelled blocks child can touch) which child's senses can detect, and child may then interpret as a communication and try to figure out the meaning of and then try to figure out how it's useful to child's current problems (which parent/teacher has only a vague conception of).
Adults forget what it's like to be a child and massively underestimate how much learning young children do. They don't realize all the details the children have to figure out. Adults take for granted lots of big conclusions they've known for ages. People start finding many of their ideas so obvious and simple that they stop realizing it could be broken down into many little pieces which are actually hard to combine into the right answer.
People have a hard time seeing the world from a perspective that's super different than their current perspective. They don't realize how little of their communications to students actually succeed. Children keep learning things, so parents and teachers assume that they taught the child. But a lot of the time the child figures out most of it on his own, doesn't understand a lot of what he was "taught", and finds a lot of other things he was "taught" useless and unhelpful.