"Those are small."
Translation:Celles-là sont petites.
See Sitesurf's answers, and this article: http://www.lawlessfrench.com/grammar/demonstrative-pronouns
"c'est petit" is as concrete as "this is small" or "that is small" or "it is small", when you comment on something with a demonstrative or a personal pronoun.
"il fait chaud, il fait froid, il est nécessaire, il faut, il pleut, il est cinq heures"... just like "it is hot, it is cold, it is necessary, it is raining, it is five o'clock..." have "il/it" not representing anyone or anything.
"ceux sont petits" is incorrect. You need "ceux-ci sont" to translate "these are" or "ceux-là sont" to translate "those are".
You can also translate "these/those are" to "celles-ci/celles-là sont".
The only construction where "celui/celle/ceux/celles" can be used without their suffixes is when they are followed by "de" or "que":
- celui de mon frère est bleu = my brother's (one) is blue
- c'est celle de ma mère = it is my mother's (one)
- ce sont ceux que je porte = they are these/those (the ones) I am wearing
- voici celles que j'ai achetées = here are these/those (the ones) I have bought.
as implied in sitesurf's answer, note that ce/cette are articles, not pronouns. Well 'ce' can also be a pronoun, in which case 'ceci' and 'cela' are the variations you were looking for. Or maybe what you were looking for is celui/celle, the true singular of ceux/celles. They too get ci-ça'd: celui-ci, celui-là, celle-ci, celle-là.
So ceux-ci = these, ceux-là = those is what Duolingo teaches. But is it right to translate them so literally?
In my grammar book it's explaines that ceci and cela (and all their forms) are used for comparisons. Ceci refers to the first or closer thing, cela to the second or more distant.
If I have a sentence like this where I refer to only one thing wouldn't I use ceci?
Because I think it's like the German "diese" and "jene" and we would always use the first option first and then additionally the second (and a third... etc). If we needed only one pronoun we would not get to the second option. Only ever the first.
Okay, maybe there was another sentence preceding this one and it had ceci in it and that's why now we need cela. But we can't know so Duo should at least accept both.
Or did I get this whole thing wrong?
It is mostly a matter of degree of emphasis:
c'est mon stylo = it is my pen
ceci est mon stylo = this is my pen
cela/ça ne coûte pas cher = that does not cost much
ceci est rouge mais cela est vert = this is red but that is green
celui-ci est mon stylo et celui-là est le tien = this one is my pen and that one is yours
The reason that "ceux sont petits" is not correct is that "ceux" can not stand alone.
"Ceux" (and "celui", "celle", "celles") must be followed by a relative pronoun, a preposition or (as in this case) a demonstrative suffix - "ci" or "la".
Checkout link for more information on demonstrative pronouns.
That is not always correct. When "ceux" follows a mention of what noun it is replacing, it can stand alone, since it is clear what it is referring to. It could be that the rules are more complicated than that, and that rules only applies in certain cases, but I can say for sure that I have seen "ceux" standing alone (outside of colloquial speech).
"ceux" can live without -ci or -là in specific cases:
- ceux de (possessive)
- ceux qui (these/those who/which/that)
- ceux que (these/those whom/which/that).
- ces livres sont ceux de ma fille
- ces hommes sont ceux qui sont venus hier
- ces livres sont ceux que j'aime le plus
- ces livres sont ceux qui me plaisent le plus
- ces hommes sont ceux que j'ai vus hier
But "ceux" cannot stand alone as a subject.