"Where do they make a journey to?"
Translation:Quo iter faciunt?
This sentence can be translated as "To where...?" or "Where...to?"
Both forms are correct in English. The former is more formal. It is not considered an error to end a sentence with a preposition, despite what some one our teachers have said.
Please refrain from reporting the sentence as an unnatural English translation.
Exactly. So, a quo? question will usually have an answer (with a verb of motion, as in the question) using an ad + accus. prepositional phrase ("to the city, to the country"). But an ubi? question will have an answer (using the same verb indicating location, not movement, as in the question) plus either a locative (Romae, "in Rome") or an in + ablative prep. phrase (in villa, "in the country house") or perhaps sub + ablative prep. phrase (as in sub arbore, "under a tree").
Corresponding to quo?, "to where?", is the adverb eo, "there, TO that place" (with a verb of motion). Corresponding to ubi? "where?", is the adverb ibi, "there, IN that place" (with a verb of position/location).
Ubi means "where", when "where" means in what location .
Where are you sitting? = Ubi sedetis?
Where are they sleeping? = Ubi dormiunt?
But as soon as motion becomes relevant, you need a different word for "where":
Where are they going? means there's motion TOWARDS a place, so: Quo eunt?
Where are they coming from? indicates that there's motion FROM a place, so: Unde veniunt?
I guess Duolingo would signal the need for a subject pronoun by saying "Those people/guys" (masc. pl. nom. illi), "Those women" (fem. pl. nomin. illae) or "Those things" (neuter pl. nom. illa). Though it's hard to imagine a group of "things" that are "taking a trip" to a certain place! (Maybe "those wagons": plaustra could be referred to as illa, those things.)
Deciding between "unde" (where from), "quo" (where to) and "ubi" (where, without movement to or from) seems as if it might be tricky because we no longer use "whence" and "whither" in English. German has retained the equivalent of "whence" and "whither" and I had difficulty there all right!
At least it will be easy to remember the word "quo" because of the film "Quo Vadis".
This rule came from academicians who were attempting to make English conform to Latin rules, and makes for some very awkward sentence structures since neither translates cleanly from one to the other. It is a relatively recent rule and has been (thankfully IMO) reversed.
Putting "ad" there is incorrect because (1) "quo" already means "to where," and (2) even if you did need "ad," you can't separate a preposition away from its object in Latin.
Pronoun subjects like "ei" are normally left out, though including it is not wrong. The best translation is just "Quo iter faciunt?" but adding "ei" is fine.