Learn Hardcore Norwegian: Jeg lager havregrøt kvelden før for at morgenen skal bli roligere. - I make oatmeal porridge the evening before so that the morning will be calmer.

Habits / routines
- Jeg lager havregrøt kvelden før
  = I make oatmeal the night before (as a regular habit).
Planned future (especially with a time expression)
- Jeg reiser i morgen. = I’m leaving tomorrow.

So lager here is a present habitual: it describes what you usually / typically do, not a single specific future event. English happens to use the present simple the same way:
I make oatmeal the night before so that the morning is calmer.

Why is there no article before havregrøt? Why not en havregrøt or havregrøten?

Havregrøt is a mass noun (like oatmeal, rice, water):

Jeg lager havregrøt. = I make oatmeal / porridge (in general, some amount of it).

You would use the definite form havregrøten when you mean the specific oatmeal:

Jeg spiser havregrøten nå. = I am eating the oatmeal (that we both know about).

En havregrøt (indefinite singular) is not natural in normal Norwegian for this food; you don’t usually count one porridge. You might say something like en porsjon havregrøt (a portion of oatmeal) if you really want to count it.

How should I understand kvelden før? Why is there no den (den kvelden før)?

Kvelden før literally is the evening before and is a fixed type of time expression:

kvelden før = the evening before (the next event, usually the morning mentioned later)
dagen før = the day before
uka før = the week before

Norwegian often uses the definite form alone as a time expression, without den:

Jeg kom hjem kvelden før. = I came home the evening before.
Vi dro dagen etter. = We left the day after.

Adding den (den kvelden før) would make it sound unusually heavy and is not standard in this kind of expression.

What exactly does for at mean here, and how is it different from for å or fordi?

In this sentence:

for at morgenen skal bli roligere ≈ so that the morning will be calmer / in order for the morning to be calmer

For at introduces a purpose clause with a full sentence (subject + verb):

Jeg gjør dette for at barna skal ha det bra.
= I do this so that the children will be well.

Compare:

for å
- infinitive
- Jeg lager havregrøt for å spare tid.
  = I make oatmeal to save time.
  Here there is no subject inside the phrase, just å spare.
for at
- full clause (subject + verb)
- … for at morgenen skal bli roligere.
  = so that the morning will be calmer.
fordi = because (reason, not purpose)
- Jeg lager havregrøt fordi jeg liker det.
  = I make oatmeal because I like it.

So for å is for to / in order to + verb,
for at is so that / in order that + sentence,
fordi is because (giving a reason, not a goal).

Why is the word order morgenen skal bli and not skal morgenen bli in for at morgenen skal bli roligere?

Norwegian has two main word orders:

In main clauses (normal sentences), the verb is usually in second position (V2):
- Morgenen blir rolig.
- I morgen blir morgenen rolig.
In subordinate clauses (introduced by words like at, fordi, hvis, når, for at), the word order is Subject – Verb – (other stuff) (no V2):
- … at morgenen blir rolig.
- … fordi morgenen blir rolig.
- … for at morgenen skal bli roligere.

So after for at, you must use subordinate clause order:
morgenen (subject) + skal (verb) + bli roligere (rest),
not skal morgenen bli roligere.

Why is it morgenen (the morning) and not just morgen (morning)?

Norwegian often uses the definite form to talk about a specific, known time period in the speaker’s situation:

om morgenen = in the morning (in general)
morgenen here = the morning (the particular morning that follows kvelden før)

In this sentence, there is a clear relationship:

kvelden før → morgenen (the morning that comes after that evening)

So morgenen is understood as the next morning in this routine.
Using just morgen here (for at morgen skal bli roligere) would be ungrammatical.

Why is it skal bli roligere and not just blir roligere or er roligere?

The phrase skal bli roligere combines:

skal: expresses intention, plan, or expected future result.
bli: to become, a change of state.
roligere: calmer, comparative of rolig.

So:

… for at morgenen skal bli roligere.
= so that the morning will become calmer / will be calmer (as a result).

Alternatives:

blir roligere
Would be more like a neutral prediction:
for at morgenen blir roligere sounds a bit off; for at normally goes with something intended, so skal fits better.
er roligere
for at morgenen er roligere is wrong: er is present state, but purpose clauses usually talk about a desired / future result.

So skal bli nicely matches the meaning: I do X so that Y will become Y-state.

What does roligere mean exactly, and when do I use roligere vs mer rolig?

Roligere is the comparative form of the adjective rolig (calm, quiet):

rolig = calm
roligere = calmer
roligst = calmest

In Norwegian, most short adjectives ending in -ig form comparatives with -ere:

billig → billigere (cheap → cheaper)
hyggelig → hyggeligere (nice → nicer)
rolig → roligere (calm → calmer)

You would normally not say mer rolig here. For these adjectives, roligere is the natural choice. Mer rolig would only show up in very marked or special stylistic contexts; for learners, you can safely stick to roligere.

Can I move kvelden før to a different place in the sentence?

You have some flexibility, but not everything sounds equally natural.

Original:

Jeg lager havregrøt kvelden før for at morgenen skal bli roligere.
(Very natural.)

Other possibilities:

Kvelden før lager jeg havregrøt for at morgenen skal bli roligere.
- Also natural; just emphasizes kvelden før.
Jeg lager kvelden før havregrøt for at morgenen skal bli roligere.
- Feels slightly less natural; you usually keep lager havregrøt together.
Jeg lager havregrøt for at morgenen skal bli roligere kvelden før.
- This sounds confusing, almost like the morning is calmer the night before, so it’s not good.

General rule:
Keep the verb + object (lager havregrøt) together, and put kvelden før near the verb as a time adverbial, preferably before the for at-clause.

Should there be a comma before for at? Is Jeg lager havregrøt kvelden før, for at morgenen skal bli roligere correct?

Both are possible in written Norwegian, but they have slightly different uses:

Without comma (as in your sentence):
- Jeg lager havregrøt kvelden før for at morgenen skal bli roligere.
  The for at-clause is felt as closely integrated with the verb phrase; this is very natural here.
With comma:
- Jeg lager havregrøt kvelden før, for at morgenen skal bli roligere.
  The comma makes the for at-clause a bit more separate and explanatory. It is not wrong, but it can feel slightly heavier in such a short sentence.

In modern Norwegian, it’s quite common not to use a comma before short purpose clauses like this, so the version without the comma is typically preferred.

How do you pronounce havregrøt and morgenen?

Approximate pronunciation (standard East Norwegian):

havregrøt: HAV-re-grøt
- ha like ha in hard but shorter
- vre with a rolling or tapped r
- grøt: grø like the vowel in French peur or German schön, then t at the end
morgenen: MORR-ne-n
- mor: often pronounced a bit like mor in English morning, but shorter; the g is usually weak or silent in many accents
- ge: here it merges into the n, so you hear something like morn-en-en
- Many speakers reduce it to something that sounds like mårn’n in fast speech.

So a rough English approximation:

havregrøt ≈ HAHV-re-grurt (with that Norwegian ø sound)
morgenen ≈ MORR-nen / MORN-en-en