A teacher sent home a list of assignments with a cover letter explaining, "These are not homework."
"This is not homework," or "These pages are not homework," sound equally normal to me, but "These are not homework," just sounds weird. Is it correct grammar?
I don't agree that the question: 'Agreement in “[Singular Noun] Is/Are [Plural Noun]”?' describes this specific usage. In "These are not homework," the word "These" is not a singular noun. It's a plural pronoun. I suspect that some of the problem is that the missing noun is implied to the reader only by the physical presence of other documents, and not contextually from the surrounding content of the cover letter itself.