Talk with the children and make up a guessing game about "where do we learn things?" Depending on their age group, the children might come up with examples such as school, the library, teacher or parents. These are larger conceptualized units and you want to work with them to make these concepts even smaller and more focused on items.
Point out places like the school and the library and ask the children to think of places within them that they can learn things from. They may come up with ideas. Try to direct them. For example, guide the conversation toward items such as books in the library or books in their classroom.
Introduce the concept of "letting people know where we learn things." Talk to the children and remind them if they received information from someone this enables them to tell others exactly where they got the information. Create an example of how, if they were given a book, they could tell their friends where they got it. Have a child give a friend a book. Then have other children ask him where he got the book.
Emphasize that being able to tell people where you got some information is considered a reference. Explain this connection by making this a story of sharing. Describe and explain how if the children receive something that they like, they can tell others where to enjoy it as well.
Explain to the children that in order to share something like a reference they need to tell their friends what it is in a way that their friends could find it even if they weren't there. Help them think of ways that this could happen and direct them to understanding that writing the information down is a really good way to do this.
Introduce basic examples of references. Ask one child to read simple information off a book, such as the author and the title, in order to learn how to write a book reference. Write this information out for them and explain that this is a form of reference and that others can use this to find and share the book they enjoyed.