Learn Hardcore Afrikaans: Ek sit nou in die klas en skryf in my nuwe boek. - I sit now in the class and write in my new book.

In Afrikaans the simple present tense (e.g. sit) covers both simple and continuous meanings. You don’t need an extra auxiliary to say “I am sitting.” If you want to stress the continuous aspect, you can use besig om te + infinitive:

Ek is nou besig om in my nuwe boek te skryf. (“I am now busy writing in my new book.”)
But it’s perfectly normal to say Ek sit nou … en skryf … for “I’m sitting now … and writing …”

What’s the rule for placing the adverb nou in the sentence?

Afrikaans follows a “verb second” (V2) word order. The finite verb (sit) occupies the second position, so most time-adverbs like nou come immediately after it:

Correct: Ek sit nou in die klas…
Not correct: Ek nou sit in die klas…

Why is die used before klas, but there’s no die before my nuwe boek?

die is the definite article “the,” so die klas = “the class/classroom.” When you use a possessive pronoun (like my), it already acts as a determiner, so you don’t add die. You say my nuwe boek (my new book), not die my nuwe boek.

Why is the preposition in used before both die klas and my nuwe boek? Could another preposition work?

in die klas means “inside the classroom” or simply “in class.”
in my nuwe boek means “inside the pages of my new book”—that is, writing within it.
You generally use in for “writing inside a book.” If you wanted to say “writing on the cover,” you might use op (on): skryf op die omslag, but for the interior of a bound book in is correct.

Why is the adjective written as nuwe and not nuut or without the -e?

Afrikaans adjectives take an -e ending in attributive position when the noun is definite or possessed. Here boek is possessed by my, so you add -e:

my nuwe boek, die nuwe boek
The only time you drop the -e is with a neuter, singular noun preceded by an indefinite ’n:
’n mooi huis, ’n nuwe boek

Why don’t we repeat ek before the second verb skryf?

When two verbs share the same subject, Afrikaans links them with en (“and”) without repeating the pronoun. So Ek sit nou … en skryf … is fine. If the second clause had a different subject, you would need to repeat ek or use another subject:

Ek sit nou in die klas en hy luister.

Does klas here mean the physical room or the lesson itself?

klas can mean either “classroom” (the room) or “class/lesson” (the session). In Ek sit nou in die klas… it usually implies “I’m in class (attending the lesson),” but it also literally means you’re inside the classroom. Context tells you which interpretation is intended.

Is nou mandatory? What changes if I omit it?

nou (“now”) gives you an explicit time reference—“right now.” If you drop it (Ek sit in die klas en skryf in my nuwe boek), you still say “I sit in class and write in my new book,” but it’s less clear that it’s happening at this very moment. You could add a different time adverb (e.g. nou, altyd, vanaand) depending on what you want to emphasize.