Hyphens, En Dashes, Em Dashes
Q. Books that can be read aloud are known as “read-alouds.” Should this term be hyphenated or not?
A. Whenever you can’t find the answer to a specific hyphenation question, an analogy can be your friend. In this case, we would tend to hyphenate “read-alouds” on the principle that it is grammatically similar in construction to the hyphenated noun form “sing-along” (the plural of which would be “sing-alongs”). Not only does “sing-along” describe a similar activity—it also has an entry in Merriam-Webster.