I found this song on paragraphs/main idea. The video does a nice job introducing paragraphs.
I showed students several examples of paragraph changes from our current read aloud Wonder. We discussed the fact that there is no specific length for paragraphs.
For example, they wrote, "The next morning..." for the change in time section.
I also made an additional foldable, if you would prefer to have students use this instead of just giving them the list of rules. I would be willing to send you this one as well, if that would work better for you.
(Foldable Template from Lovin Lit)