When you think of writing for kids you need to understand that there are rules and regulations defined by the industry. There are stories for kids which involve these characteristics:

• Children book illustration: these books are for kids with an average age of 8.
• Simple reader books: these books are for children between the ages of 5 to 9. The word count and the reading level is depended on publisher and reader respectively.
• Chapter-wise book: These are brief children's books from 7 to 10 years of age.
• Young children novels: These books are written for children aged between 8 and 12 years.
• Young Teenager novels: Such books are written by children aged 12 and up.

On which factor are you going to work?