Children's plots must be built around believable characters trying to solve kid conflicts. ... Picture book plots can be very simple and revolve around everyday conflicts such as learning to make friends or a walk in the forest. Conflicts for easy readers often focus on action, involving school settings and friendship. Older readers are able to grasp more complicated concepts, but they still want to read about kids their age dealing with kid problems.
Here are 3 tips for developing a plot for your children's book:
The beginning must hook young readers. The best way to do that is to plop readers right in the middle of your story. When writing for kids, there is no time for lengthy descriptions, details or back story.
The middle of a children's book is a series of cause-effect relationships. This chain-sequence of cause and effect builds in intensity toward a moment of do-or-die decision.
Endings wrap it up.
The ending of the plot revolves around a crisis or climax, during which the conflict question is answered. No matter how your story ends, remember that your main character should show some growth, either emotionally or intellectually and that all loose ends of your story should be satisfactorily tied up.