Showing grammatical case next to sentences
As I go through the course it's often very hard to figure out what grammatical case a given word (noun, ...) has, particularly when cross-referencing with a dictionary and it turns out that a given noun has the same inflection for several cases.
Often, someone in the discussion points the grammar case out (and hopefully it's correct), but not always.
Would it be possible to include grammar case somewhere in the lesson (e.g. when you hit "check" and it shows the correct answer, it'd be great if in parentheses there was a note what grammar case it has. Or it could be included in the popup when you hover over a word)?
It would be nice, but I think it would be an impossible amount of work for the course constructors.
A good start point is to look closer at the case the word would be in English. And, where that doesn't seem to work, at least try to understand what "part of speech" that word is in the same sort of English sentence - where it's less obvious because we don't often change the word because its case changes.
Nominative and accusative, if it's because they're subject and object, are easy to work out if you understand the construction of a sentence in English.
Anything after a preposition will be in its appropriate case because that's what the preposition demands - occasionally changing because there's motion involved, or not. You really need to learn the common prepositions and which case they need as a separate excercise from doing the lessons here.
Vocative - only when you're talking directly to it - "Hi, parrot" and "parrot" is in the vocative.
Sorry but I can't do the lot right now, and there are people here who can explain it quicker and more accurately than me, and there are some quirks and exceptions that I'd probably miss. But you get the general idea.
I don't think that's necessary. The point of the Tips and Notes is to give you enough knowledge of the grammar to figure out the sentences on your own. But, I can offer some tips to help you get under way.
My advice to you is to find the verb first. When you see a sentence like "puer sorores habet", the fact that "habet" is singular third person already tells you that "puer" is nominative, as "sorores" cannot be nominative because the verb doesn't allow for plural. It also cannot be vocative because there's no indication of talking to anyone (we're not addressing anyone directly). So it has to be accusative. The boy has sisters.
Now, cattae sorores habent could technically be interpreted in two different ways: the cats have sisters or the sisters of the cat have. Both of these are correct, but due to Latin's primarily SOV word order, I would be more likely to use the first translation (and also because genitive usually comes after the noun being possessed - not before, like here).
With a sentence like "fratres sorores habent," things become a little dicier. The verb is third person plural, but both these nouns are plural - so either of them could be nominative. (We can rule out vocative because there's no indication of talking to anyone here.) So, brothers have sisters and sisters have brothers are both technically correct. However, once again, due to Latin being primarily SOV word order, I would prefer "brothers have sisters" as a translation.
Dative is actually pretty easy to tell. Flores puellae do. By looking at the verb, I can already rule out either of these nouns being the subject, because I is the subject - I give. So, once again, since nominative is occupied, this leaves accusative to be found. The form "puellae" cannot be accusative, but "flores" can. So, I give flowers. Now I can turn my attention to "puellae". Since we already know this word isn't nominative, that leaves genitive and dative. I could translate the sentence to "I give the girl's flowers", but to me a more natural solution is to use the dative - "I give flowers to the girl."
In the case of the sentence you posted as an example, if I look at the verb, I see that it is third person singular - this rules out "fratres et sorores" as the subject, because the verb indicates a singular subject. And then there's Marcus - being second declension, it's easy to tell if it's nominative or accusative; in this case it's nominative. So Marcus is the subject - putting together the subject, the verb, and the question word, we get "How many ... does Marcus have?" The only thing left to fill in the blank is "fratres et sorores" - so the answer is "How many brothers and sisters does Marcus have?"
So, my recommendation: find the verb, identify the nominative, identify the accusative, and then worry about the "flavor" words (as I often call the words in the last three cases). Use Latin word order as a guide if you get stuck. See if that helps you any.
Good luck! :)
Volgav vitsenanieff nivya kevach varatsach.