In order to differentiate instruction, the teacher can pair students in need of assistance with students who understand the concept during small group time.
Provide struggling writers with sentence frames to write their narratives.
Display the anchor chart or a word bank to ensure all students can think of adjectives/details.
Provide a revising/editing checklist for students on an as needed basis.
An extension activity would be to have the students work on writing a fantasy narrative about a school that is underwater, allowing them to work together to describe how a student at this school learns, gets to school, does at recess, etc.
Another extension activity would be for the students to make a graphic organizer of different categories of descriptive words (color words, size words, etc.). They can go around the classroom finding ways they can further describe objects.
Students could create a class book of WOW sentences (using describing words) and a class book of BLAH sentences (without describing words)