The most reliable source for a presentation about education in multi-age classes would be a 1. school textbook for students. 2. parenting blog about student mentors. 3. wiki website about the history of one-room schoolhouses. 4. journal article about classrooms with students of varying ages.

nature versus humanity!

the answer is:

when will (v) the books (n) be (v) due?

nouns refer to people (other than pronouns), places and things, whereas verbs describe actions and are usually part of the predicate of a sentence. finally, pronouns can work as nouns and identify the participants in speech.

in the example sentence, "will" is a verb part or auxiliary verb, "be" is an infinitive verb and "books" is a plural noun.