Learn Hardcore German: Mein Bruder malt im Wohnzimmer. - My brother is painting in the living room.

Bruder is a masculine noun: der Bruder.
In this sentence, Bruder is the subject, so it is in the nominative case.
The nominative masculine form of mein is mein (without -e).

Some forms of mein (nominative):

mein Bruder (masculine)
meine Schwester (feminine)
mein Kind (neuter)
meine Brüder (plural)

So Mein Bruder is correct because Bruder is masculine singular in the nominative case.

Why is Bruder capitalized?

In German, all nouns are capitalized, no matter where they stand in the sentence.

Bruder is a noun, so it must be written with a capital B.
The same applies to Wohnzimmer, Tisch, Auto, Freundin, etc.

Verbs (malt), adjectives (groß), and most other words are not capitalized unless they start a sentence or are part of a proper name.

What is the infinitive of malt, and how is it conjugated?

The infinitive is malen (to paint).

Present tense conjugation of malen:

ich male – I paint / I am painting
du malst – you paint (singular, informal)
er/sie/es malt – he/she/it paints
wir malen – we paint
ihr malt – you (plural, informal) paint
sie malen – they paint / you (formal) paint

In Mein Bruder malt im Wohnzimmer, Bruder is like er (he), so we use malt (3rd person singular).

Why can Mein Bruder malt im Wohnzimmer mean both My brother paints in the living room and My brother is painting in the living room?

German usually uses one present tense (the Präsens) where English has two: simple present and present continuous.

So:

Mein Bruder malt im Wohnzimmer.
can mean:
- My brother paints in the living room. (habit / regular action)
- My brother is painting in the living room. (right now)

Context or time expressions (like jetzt, immer, gerade) clarify what is meant:

Mein Bruder malt gerade im Wohnzimmer. – My brother is painting in the living room right now.
Mein Bruder malt immer im Wohnzimmer. – My brother always paints in the living room.

What does im mean, and why not in dem Wohnzimmer?

im is a contraction of in dem:

in = in
dem = the (dative, masculine/neuter)
in dem → im

Wohnzimmer is a neuter noun: das Wohnzimmer.
In this sentence we describe a location (where something happens), so in takes the dative case: in dem Wohnzimmer → im Wohnzimmer.

So:

Mein Bruder malt in dem Wohnzimmer. – grammatically correct but less common.
Mein Bruder malt im Wohnzimmer. – normal everyday phrasing.

Why is it im Wohnzimmer (dative) and not ins Wohnzimmer (accusative)?

The preposition in can take dative or accusative depending on the meaning:

Dative = location (where?)
Accusative = direction (where to?)

Here we are talking about where he is painting, not where he is going, so we use dative:

Mein Bruder malt im Wohnzimmer.
– He is painting in the living room. (location → dative: in dem → im)

If you talk about moving into the living room, you use accusative:

Mein Bruder geht ins Wohnzimmer.
– He is going into the living room.
(in das Wohnzimmer → ins Wohnzimmer, accusative for direction)

Can the word order change? For example, can I say Im Wohnzimmer malt mein Bruder?

Yes, you can change the word order, as long as you respect the verb‑second rule (the conjugated verb stays in 2nd position).

Some correct variants:

Mein Bruder malt im Wohnzimmer.
Im Wohnzimmer malt mein Bruder.
Heute malt mein Bruder im Wohnzimmer.

In all of them, the finite verb (malt) is in position 2:

2: Im Wohnzimmer (1st idea) | malt (2nd) | mein Bruder (3rd)
3: Heute (1st) | malt (2nd) | mein Bruder (3rd) | im Wohnzimmer (later)

Changing word order can emphasize different parts:

Mein Bruder malt im Wohnzimmer. – neutral.
Im Wohnzimmer malt mein Bruder. – emphasizes the location.

What does Wohnzimmer literally mean, and why is it one word?

Wohnzimmer is a compound noun made from:

wohnen = to live (reside)
das Zimmer = room

So das Wohnzimmer literally means the living room (the room where you live/spend time).

German very often combines words into one long noun:

Wohnzimmer – living room
Schlafzimmer – bedroom (schlafen = to sleep)
Kinderzimmer – children’s room (das Kind = child)

All noun parts are written together as one capitalized word: Wohnzimmer.

How would I say My brothers are painting in the living room?

You need the plural of Bruder and the plural verb form:

My brothers are painting in the living room.
→ Meine Brüder malen im Wohnzimmer.

Changes:

Bruder → Brüder (plural, with umlaut)
mein → meine (because plural nominative)
malt → malen (3rd person plural)

How would I say I am painting in the living room or We are painting in the living room?

Use the appropriate subject pronoun and verb form:

Ich male im Wohnzimmer. – I am painting in the living room.
Wir malen im Wohnzimmer. – We are painting in the living room.
Du malst im Wohnzimmer. – You are painting in the living room. (informal singular)
Ihr malt im Wohnzimmer. – You (all) are painting in the living room. (informal plural)

Same structure as Mein Bruder malt im Wohnzimmer, only subject and verb form change.

How do I negate the sentence? Where does nicht go?

A natural negation is:

Mein Bruder malt nicht im Wohnzimmer.
– My brother is not painting in the living room.

Here nicht comes before the phrase you’re negating (im Wohnzimmer).

Nuances:

Mein Bruder malt nicht im Wohnzimmer, sondern in der Küche.
– He is not painting in the living room, but in the kitchen.

If you want to negate the whole action more generally, you can also hear:

Mein Bruder malt im Wohnzimmer nicht.
This is possible but sounds more marked and often implies a contrast (e.g. he doesn’t paint there, he just sits there). For simple, neutral negation of the location, Mein Bruder malt nicht im Wohnzimmer is best.

Is malt the same as draws? What is the difference between malen and zeichnen?

German distinguishes between:

malen – to paint (with paint, colors, brushes, sometimes crayons or colored pencils)
zeichnen – to draw (with pen, pencil, etc., lines/contours)

So:

Mein Bruder malt im Wohnzimmer.
– He is painting (probably with paints or colors).

If he is drawing with a pencil, you would say:

Mein Bruder zeichnet im Wohnzimmer.
– My brother is drawing in the living room.

How would I say My brother is painting the living room (painting the walls) instead of in the living room?

Then Wohnzimmer is the object being painted, not the location. You normally wouldn’t use malen, but verbs like streichen or anstreichen for walls/rooms:

Mein Bruder streicht das Wohnzimmer.
– My brother is painting the living room. (painting the walls)

Using malen with a room (Mein Bruder malt das Wohnzimmer) would sound like he is artistically painting a picture of the living room, which is not the usual meaning for painting the walls.