I don't get this so well... so, nouns are modified according to the article or are they like the adjective's inflection? Because in another genitive case I thought that boy would be "Junges" but it was "Jungen"...
Not sure what 'name' you are referring to. There are three inflection classes for nouns in German:
1) strong nouns (like 'der Tag')
2) weak nouns (like 'der Junge')
3) nominalised adjectives (like 'der Alte')
http://en.wikipedia.org/wiki/German_declension#Nouns Nominalised adjectives get inflected exactly like adjectives, so for them inflection also depends on the preceding article.
Oh! All right, thanks! So 'des Jungen' doesn't get the same inflection as 'des Tages', that's what I didn't understand :)
That is the last hour of the day. Can anyone tell me why Tages comes in plural in this sentence?
Are -es and -e always interchangeable, then, or is it just this particular word? "des Mannes" and "des Manns" would work too?
You probably mean "-s and -es"
Short answers: no, yes.
It does work for 'Mann' but you can't substitute 'es' everywhere. E.g. it's "des Meisters". "Des Meisteres" wouldn't work. If in doubt, your dictionary will tell.
According to the description, "es" is for most single-syllable words while only an "s" is needed for multiple syllable words. It also said that the "es" is often shortened to just the "s" in colloquial speech.
Strictly speaking "Tages" is more correct ("des" or "of the" is the clue that the word it refers to has a special ending), but "Tags" is ok too.
By my understanding, dieses does not work here. You would use dieses as a pronoun for something neuter, like das Buch, where it would mean "this one". If you simply mean "this" you can use das or dies (German is not as exact about the distinction between "this" and "that" as in English).
I see what your saying and it is correct for nominative and accusative but this is genitive. Dont you not need to decline dies to the masculine genitive in which case it would have the ending -es.
The only genitive part of this sentence is des Tages. The das/dies part is nominative.
A "correct translation" of "Stunde" in my case was "lesson" Now I used "Period" which in my part of the world - Scotland - means Lesson. I reported it hoping Duo will include that in the dictionary
I've read that the Genitive case is rarely used anymore in spoken German. Could someone give me a link explaining why, and what it has been replaced by? As an English speaker, Duo's lessons seem perfectly suitable for normal speaking.
It doesn't (although the plural of a neuter object (and other objects) will always use die in nominative or accusative case). Where did you get the idea that it does?
Der, die, das all mean "the". Das is special, because it can also mean "that" when it is not immediately followed by a noun.
If you've mentioned the noun that you're talking about already, you can be more specific and use the gender-matching demonstrative pronoun instead.
Oh, Thx! That's what it was. So if I mentioned something feminine, I can just say"die..." In place of Das.?
I think so... but a native-speaker might be able to answer you more confidently.