Childrens' reading books

I went to the library today and had a look at childrens' reading books and the different levels different ages can read so we get an understanding of how simple or complex the book needs to be.
This story is a 5yr olds reading book- very very simple, with only the person/animal changing in the sentence each page. The guy at the library said our idea was interesting how we are trying to join the idea of play with reading which could encourage children to read too.