写る and 写す: appearing in a photo and copying content
Compare a person appearing in a photo with taking the photograph, and examine 写す for copying written content.
Who appears in a photograph
この写真には祖母も写っています。 says that the grandmother also appears in this photo. With 写る, read うつる, the photographed person is the subject.
逆光で顔が暗く写りました。 says that a face came out dark because of backlighting. It describes the image, not the face itself becoming dark.
Capture something in a photo
庭の花を写真に写しました。 says that someone photographed the garden flowers. With 写す, read うつす, the flowers are the subject matter and 写真に indicates the photographic form.
全員が写るように、少し下がって撮りました。 says that the photographer stepped back a little and took a photograph so everyone would be in the shot. Distinguish the action 撮る from appearing in the result with 写る.
Copy written content
黒板の文をノートに写しました。 says that someone copied a sentence from the board into a notebook. 文を marks the content, and ノートに where it is recorded.
写し間違いがないか、元の文と比べてください。 asks someone to compare the copy with the original for copying errors. 写す can mean reproducing content rather than understanding or summarizing it.
What role does the notebook have in 黒板の文をノートに写す?
Show the answer and why
It is where the sentence is copied. The sentence on the board is the content, and ノートに marks the destination of the writing.