Moving a narrator from oral to written narrations should be a gentle crossover, with the skills and needs of the narrator always the priority. A narrator will never leave oral narration completely behind, but as they progress through the years should add to them and replace the number of them with other variations of narration. For example, while my high school student still orally narrates sometimes, more often she writes narrations, essays and other papers as well as participates in deep discussions with me about what she has read.
Here are what I would consider some important points to consider:
1. Be sure that your oral narrator is fully ready to write. Your young student should be able to write a number of sentences without feeling any strain physically or mentally.
2. Cut whatever was your typical amount of reading material for oral narrations down again. Remember, in the beginning, your very young child could not successfully narrate orally a full chapter. The chapters in the early years are divided into halves and are narrated in sections. Eventually, the child is able to narrate the entire chapter, depending on the length and type of book from which they are narrating. Currently, my younger daughter is reading The Story of the Thirteen Colonies. I have her read much less than one chapter (dividing it into halves and sometimes thirds) and narrate it in sections. This particular book is filled with changing people, events and times, so cutting the amount of material to be read and narrated is really essential to me. On the other hand, she easily read full chapters from Bleak House by Charles Dickens and wrote lovely, detailed narrations in her narration notebook summarizing the events of each chapter without any hesitation. Her skills are there, but I place a different priority on some books over others, particularly with regard to fiction vs. nonfiction. If your student has been orally narrating a full chapter, then you may need to cut this back as you begin written narrations. Moving from oral narrations to writing pages and pages for written narration will become overwhelming very quickly.
Here is an excerpt from an article from the Parents' Review on "We Narrate and then We Know":
Do regulate the length of the passage to be read before narration to the age of the children and the nature of the book. If you are reading a fairy story, you will find that the children will be able to remember a page or even two, if a single incident is described. With a more closely packed book, one or two paragraphs will be sufficient. Older children will, of course, be able to tackle longer passages before narrating, but here too, the same principles should be applied, that the length varies with the nature of the book.
3. Be sure that you are always preparing the reading selection ahead of the reading. For example, go over any words which your student may need help in defining or pronouncing. Map work for knowing and understanding any important locations should be done before reading books, especially those being used for history and geography. Ask your student to recall what events and people were important in the last chapter read.
Here is more from "We Narrate and then We Know":
Do always prepare the passage carefully beforehand, thus making sure that all the explanations and use of background material precede the reading and narration. The teacher should never have to stop in the middle of a paragraph to explain the meaning of a word. Make sure, before you start, that the meanings are known, and write all difficult proper names on the blackboard, leaving them there throughout the lesson. Similarly any map work which may be needed should be done before the reading starts.
These aspects of narration are almost always forgotten in the many conversations about narration. I rarely see these points addressed in what is currently available today for CM and, if they are mentioned, they are seldom part of regular narration discussions from those who use any one or more of these curricula. These points are part of the main backbone to my curriculum. They make part of the difference between narrations being a form of writing with no purpose to narrations being a form of writing with a very great focused purpose. This is important and should be given due attention.
4. If your child wants to share more than they are prepared to write, consider letting them dictate some of it to you. Perhaps they could write the first few sentences and then let you finish the narration. Let your child give the narration a title and perhaps even a picture sometimes too.
5. Only a couple of narrations each week are expected the first year that you are transitioning. The remaining narrations can be in other forms such as oral, creative (picture, poem, skit) or other forms of written work (lists, letters, etc. ).
6. Don't be overly concerned with the conventions of writing at this point. Once my students have had a chance to get comfortable with keeping a narration notebook, I then begin to make comments into their notebook. I mix positive comments with points of correction. I might point out a capitalization problem and a spelling problem along with a compliment on word choice, for example. I tend to treat narration notebooks similarly to how I treat dictation. There is an eye towards noting that particular child's skill weaknesses and towards incrementally increasing the expectations.