seekhimfirst,
This is a really good question, and one that gets into the finer points of writing.
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I'll do my best to answer from my perspective to show the direction HOD takes with this.
To me, CM style oral narration, which later becomes written narration, focuses on the child making sense of what was read by sharing what stood out to him/her in the reading. They are to originally do this by borrowing words and phrasing from the author and eventually move toward more ownership of their narrations (still narrating in the style of the author's writing but not really reciting word-for-word anymore what the author said). Rather than looking for a certain series of main points, the child is to share what struck him/her from the reading, making the narration process personalized to each child, rather than looking for a one right answer type of narration where everyone's narration looks the same.
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The skill of orally narrating in this manner leads very well into written narration done in this same manner. So, written narrations aren't meant to necessarily be a summary, but instead to share the flavor of the author's writing from the reader's perspective.
Some children are more drawn to summarizing simply because they are "big picture" thinkers. My oldest son is definitely that way. So, narrating in a more summary-like manner for him does not make that type of narrating "wrong", but if I start looking for him to include certain key points and requiring him to have those in his narration, then the lesson has strayed into a summarizing lesson rather than a narrating opportunity.
I will share that even though my oldest son thinks in main idea steps, his narrations still capture the flavor and style of the author, which is another key difference in summarizing versus narrating. Written summaries are often written more like an outline or like a note-taking exercise where details are not abounding and using wording from the author or of your own style is not a focus. Instead, a summary often reads like a succinct paragraph where there is little extra flavor and where the author's style is not evident.
In contrast to my oldest son, my next son in line is a detailed child.
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He is very descriptive in his narrations and can get very lengthy when narrating, yet does it beautifully. I share this to show you that although my two oldest boys are so different in their approach to narrating, yet they both are doing it well. One in a more summary fashion (in the author's style) and one in a very descriptive fashion (often giving very long narrations). Yet, both are good writers both creatively and also in more formulistic settings like with the Medieval Writing Lessons, even though my boys may differ greatly in their narration style.
So, now with the groundwork laid, we come to your question. I see summarizing as an important skill that is taught best through outlining and later note-taking of more textual material, such as that found within history and science books. Using classic literature for a summary exercise means that much of the flavor and style of the story is being lost in the focus to get the main ideas down on paper. Where narration, in contrast, is a child's opportunity to share what struck him/her in the reading and what made the reading memorable to him/her. While this at first may not seem as important of a goal as being able to summarize, in truth it is the sifting and sorting and deciding which information to share that is the "work" of narrating which leaves the impression on the child's mind for years to come.
At HOD, we teach summarizing through outlining and note-taking through the Rod and Staff lessons and also through some of our writing programs such as Medieval History-Based Writing Lessons. Since summarizing is definitely a more formulistic skill, more in the "one right answer" vein, in our opinion it fits best in that category, as it takes much of the personal part out of writing. It is a necessary skill and one I think comes more into focus as kiddos get older and have a need for it. But, I will say that my two oldest sons can both summarize easily, which I think comes from years of sifting and sorting through what they want to say (or write) within their oral or written narrations for the living books we've scheduled throughout HOD.
I hope that helps a bit as you ponder through this.
Blessings,
Carrie