I buy clothes whenever my clothing gets old. (What is a noun clause?)

(Grammar Questions I Couldn't Answer)

In a previous entry in this series, I admitted that I don't fully understand what a noun clause is.

The question of noun clauses came up again in a recent staffroom discussion.

A co-worker asked me for my opinion on something he had noticed from the textbook (Reflect Listening & Speaking 5, Unit 2, Grammar: Noun Clauses p.34-35).

"I think I get noun clauses," he explained to me.  "It's a clause that acts as the subject or the object of a sentence.  I get that part.  But how do you explain this?"

He then directed my attention to the grammar explanation box on page 34, which read:

whoever, whenever, whatever

When the noun clause begins with whoever, whenever, or whatever, the meaning is "anyone, any time or anything."

We aim to give our customers whatever they want.

Okay, so far so good.  In the example sentence above "whatever they want" is obviously a clause, and it's obviously standing in the place of a noun.  (You can test this out by substituting a noun into the same slot--e.g. "We aim to give our customers a hat."  The sentence is still grammatical either way.)

But then, my co-worker directed by attention to Exercise J on page 35, in which the students were given sentence heads that they had to complete.

Number 2 of exercise J reads: "I buy new clothes whenever_______________"

My co-worker explained to me, "I tried to complete the sentence myself, like 'I buy new clothes whenever I feel sad', but then it's not functioning as a noun, right?"

I agreed.  "Yeah, that seems like a time adverbial to me.  So I would call that an adverbial clause, not a noun clause."

We checked the teacher's book to see what the suggested answer for this exercise was.

Now of course, because of the open-endedness of the prompt, the answer key said "answers may vary, but here are some possible answers."  Then, the possible answer for number 2 was: "I buy new clothes whenever my clothing gets old."

Both my co-worker and I were of the opinion that this was an adverbial clause, not a noun clause.  (Its not functioning as a noun in this sentence?  I mean, it's not a subject, it's not an object, it's not an indirect object, it's not a predicate nominative, etc.)

So, what was going on here?

The easiest option is that the textbook was just wrong.  

In my experience, in my many years in TESOL, it's not uncommon for mistakes to get printed in textbooks.  In fact, it happens quite often.  This could just be a mistake.

Right?  Or have we analyzed this sentence wrong?  Let me know in the comments if you disagree.

"So," asked my co-worker, "What about the word 'whenever' then?  Can it ever be used with a noun clause? (as the textbook claimed on page 34)  Or is it only used as for adverbial clauses?"

We tested out some examples.  My co-worker thought of, "I hate whenever you look at me", and he argued that this could possibly be a noun clause starting with "whenever".

But I argued that his sentence was ungrammatical.  It should be "I hate it whenever you look at me."  We debated for a while whether or not the "it" was necessary.

In the end, we never did come to a conclusion about whether or not "whenever" could be used with noun clauses.