The grammar hiding in a bedtime story
A learner will meet a structure forty times in a book they love and once in the lesson about it. Only one of those is doing anything.
There is a structure in English that learners find genuinely hard: the one for talking about things that are not true. I wish I could. If I were taller. She would have come. It combines a tense that is not really about time with a modal verb, and no amount of being told the rule makes a child able to use it.
It is also everywhere in stories for young children, because wanting what you do not have is what most children's books are about. Which means a learner meeting this structure in a picture book is meeting it in the one place it makes immediate sense — attached to a character who wants something, in a situation where the wanting is the point.
Why the rule does not transfer
You can explain to a ten-year-old that 'wish' takes a past form to signal unreality, and they can repeat that back, and they will still say 'I wish I can go' the next day. This is not a failure of attention. Explicit knowledge about a language and the ability to produce it live are close to separate systems, and the second one is built from encounters rather than explanations.
What the encounters need to be is frequent, meaningful, and unremarked. A child needs to meet the pattern many times in situations where they care what is being said, without anyone stopping to point out that a pattern is occurring. Stop and point, and the sentence becomes an example — which is a different and much less useful thing to a learner than a sentence that was just being said.
What a story does that a worksheet cannot
Repetition without tedium, first. A book a child likes gets read again and again, and each reading is another pass through the same structures with full attention, because the child is there for the story rather than the grammar. Nobody rereads a worksheet.
Emotional stakes, second. 'I wish I could drive' means something when a small character is stuck on a play rug looking at a real car. The same words in an exercise are inert. Learners remember language attached to feeling, which is why the vocabulary of a favorite book turns up in their speech and the vocabulary of a vocabulary list does not.
And a reason to notice the contrast, third. Books about wanting almost always put the wanting next to the having — the young character who wants to be older, next to the older one who wants to be young again. That pairing hands a learner two versions of the same structure back to back, which is exactly the comparison a grammar exercise is trying and failing to engineer.
How to use it without ruining it
Read the book several times first with no agenda at all. The structure needs to be familiar before it can be examined, and a book that got interrupted for a lesson on the first reading may not get requested for a second.
Then, later, do the smallest possible thing: say your own version out loud in the same shape. I wish I could fly. I wish I could eat this whole cake. A child will usually produce one back without being asked, because you have made a game rather than a task. That is the entire technique.
If you want it written down, keep it to the same frame with a blank in it, and let them fill it with anything at all, including something silly. What you are practicing is the shape. The content can be nonsense and the learning is identical.
The structures worth watching for
Beyond wishes: comparatives, which almost every picture book about growing up runs on. Sequencing words — first, then, after that — which stories deliver naturally and conversation rarely does. Question forms, in any book where a character asks things. And the past tense, which arrives free with any story told as something that already happened.
You do not need to plan around these. You need to notice which ones a book you already own happens to be full of, and then read that book more often than the others while it is doing its work.
The version of grammar teaching that works with young learners barely looks like teaching. It looks like reading the same story a lot, saying a sentence in the same shape as one from the book, and letting a child say a sillier one back.
The rule can come later, when they are older and already fluent enough to find it interesting. By then they will not need it, which is roughly the point.