Ce vs. Ces (of course Cette as well)
I thought I had this but obviously not. I was under impression, that Ce is masculine (Cet before vowel), Cette feminine and Ces plural.
I keep loosing hearts on occasion because the sentences are supposed to be : " Ce sont ....." How come it is not "Ces sont "???
My understanding is that 'ce' is invariable when used as a pronoun. So, if it's the object of the sentence, and there's no noun directly after it, it will always be 'ce', no matter what. However, 'ce' is also an adjective, and here it would change depending on the noun it describes. So, in your sentence, it acts as a pronoun, and even though the verb is plural, it cannot change. It would change if it were: 'ces hommes sont grands', for example, because it describes the noun 'hommes'.
You may wish to get a second opinion - I am not 100% sure that this is correct!
This is a really good question of kacenka9's. Like WordJigsaw, I hope someone who knows French grammar well will speak up, but having spent the last several minutes looking into this, here is what I've found. It sounds like you are right, WordJigsaw:
about.com only refers to this: http://french.about.com/od/grammar/a/indefinite-demonstrative-pronoun.htm . See the 2nd paragraph. It would be nice if she'd given an example with "ce sont"
this online page treats "ce" as a neuter demonstrative pronoun: http://www.synapse-fr.com/manuels/CE.htm . See especially the 3rd, longest, paragraph.
in a Russian school grammar from the 1990s that I have, "ce" is also treated as a neuter demonstrative pronoun when used this way. Since kacenka9 knows basic Russian (which is also all I know), here is the most relevant bit, in which the Russian examples use a similar construction (ce = это):
Глагол-связка согласуется в числе с именной частью сказуемого, а не се подлежащим, выраженным местоимением ce (The linking verb agrees in number with the nominal part of the predicate and not with the subject expressed by the pronoun ce):
C'est un étudiant. Это студент.
Ce sont des étudiants. Это студенты.
Well, that probably took more time and space than it is worth, but there it is. Again, I hope someone who knows French well will comment.
(tried to reformat, a couple of times)