When we think about children's books, many of us do not think of them as being "logical." After all, talking animals, zany happenings and strange events are often a part of these stories! However, no matter how strange the things that are happening in the book seem, an important part of how you learn to write is going to be focused on keeping your story logical. The thing to remember is that no matter how fantastical or strange these books are, they still have rules and a good story will abide by the rules that it has created. Logic is an important part of children's books, and if that is what you want to write, there are a few things that you should keep in mind.
When you sit down to write a children's book, remember that you should think about the world that you are interested in creating. Is it a world where mice live and act just like humans or is it a world that is essentially unrecognizable from the one that we know and live in? If you are concerned about moving forward and making sure that the world is a good one, you are going to need rules. You are setting up the logic for your story and your story must follow it. Even if the rules are different from the ones that we know are true, you must stick with them!
For instance, when you are creating a story, think about what needs to have happen. It is important that your character go through fascinating things or that they are able to complete interesting or daunting tasks. However, if they are able to finish the tasks to simply, no one is going to be interested in the story, and if they somehow magically finish the tasks for no good reason and without conflict, you are cheating your reader out of a satisfying story! Your character's conquest needs to be a logical conclusion of the things that have come before it. Unless you can make the victory seem plausible, you are looking at a book that is not going to do well.
If you have a magical item in your story, remember that it should work under its own rules. In Snow White's story, the poisoned apple would poison everyone who bit into it, and the queen's magic mirror always tells her the truth. What a poorer story it would have been if the poisoned apple didn't work or if the magic mirror could lie! Snow White might have been safer, but it would not have been much of a story would it. Learn to write great children's stories by taking some time to think about the logic in your children's books and how they work.
When you are interested in children's books and want to learn to write them, logic is one of the best lessons that you can pick up. Take some time and consider what your options are going to be and how you can keep your logic consistent; this is an essential part of writing and moving forward.