Learn Hardcore Czech: Když je celá rodina doma, je moje babička šťastná a dědeček není smutný. - When the whole family is at home, my grandmother is happy and grandfather is not sad.

After a conjunction like když, it is very common for the verb je to come early in the clause.
Když je celá rodina doma feels neutral: When the whole family is at home…
Když celá rodina je doma is not wrong, but it sounds a bit marked, with extra emphasis on celá rodina (the whole family, not just some of them).

So the sentence you see is simply the most typical, unmarked word order.

Why is rodina (family) treated as singular in Czech, even though it’s a group?

In Czech, rodina is grammatically singular feminine, just like žena (woman) or kniha (book).

celá rodina = whole family (singular feminine)
The verb agrees with this: rodina je doma (the family is at home), not rodina jsou doma.

This is different from English, where we sometimes treat family as plural (e.g. my family are… in British English). In Czech, you always use singular agreement with rodina.

Why is it celá rodina, not celou rodinu or something else?

Celá rodina is in the nominative case, because it is the subject of the clause.

rodina – nominative singular (who/what is at home? the family)
celá – adjective meaning whole, feminine singular nominative

The forms change with case:

nominative: celá rodina (subject)
accusative: celou rodinu (object – e.g. vidím celou rodinu = I see the whole family)

In this sentence, the family is doing the “being at home”, so it must be nominative: celá rodina.

What is the difference between když and až or jestli? Why is když used here?

Here když means when(ever) and introduces a time clause.

Rough guide:

když – when/whenever (general time, repeated situations, also sometimes “if”)
- Když je celá rodina doma, babička je šťastná.
až – when (in the sense of “once / after that time in the future”)
- Až bude celá rodina doma, babička bude šťastná.
  Once the whole family is home, Grandma will be happy.
jestli – if (condition, not time)
- Jestli bude celá rodina doma, babička bude šťastná.
  If the whole family is home, Grandma will be happy.

In your sentence we are describing what usually happens whenever the family is at home, so když is the natural choice.

Why is there a comma after doma?

Because Czech separates a dependent clause from the main clause with a comma, especially when the dependent (subordinate) clause comes first.

Structure:

Subordinate clause: Když je celá rodina doma,
Main clause: je moje babička šťastná a dědeček není smutný.

In English you also usually put a comma when a dependent clause comes first (When the whole family is at home, my grandmother is happy…), so this punctuation rule is very similar.

Why is doma used without a preposition instead of v domě or v domě doma?

Doma is an adverb meaning at home. It already includes the idea of “at”:

Jsem doma. – I am at home.
Rodina je doma. – The family is at home.

V domě literally means in the house (building). You would use it if you emphasize the physical building rather than the idea of “home”:

Je v domě. – He/She is in the house (not outside).

In your sentence, the idea is about home and family being together, not about the physical building, so doma is the natural choice.

Why do we have je twice in the sentence – in když je celá rodina doma and again in je moje babička šťastná?

Because there are two separate finite clauses, and each needs its own verb:

Když je celá rodina doma – subordinate clause (verb je)
(tak) je moje babička šťastná a dědeček není smutný – main clause (verbs je and není)

You cannot “share” je between clauses. Each clause must have its own finite verb.

The only place where je is not written is before dědeček in the phrase a dědeček není smutný – there, you see není, the negative form of je.

Why is it moje babička and not má babička? Are both correct?

Both moje babička and má babička are correct; they mean the same (my grandmother). The difference is style and frequency:

moje babička – full form, very common in everyday speech
má babička – shorter, a bit more formal or stylistically elevated; also common in writing, poetry, etc.

In spoken, neutral Czech, learners are usually safer using the full forms:

moje, tvoje, jeho, její, naše, vaše, jejich

You will often hear the short forms too:

má, tvá, její, naše, vaše, jejich

So you could say:

Když je celá rodina doma, je moje babička šťastná…
Když je celá rodina doma, je má babička šťastná…

Both are fine.

Why is šťastná ending with -á, but smutný ends with -ý?

The adjective ending agrees with the gender of the noun:

babička – feminine, singular
dědeček – masculine animate, singular

So:

feminine singular: šťastná babička
- šťastn- (stem) + -á (feminine singular ending)
masculine animate singular: smutný dědeček
- smutn- (stem) + -ý (masc. animate singular ending)

If we swap genders, the endings change:

šťastný dědeček – happy grandfather
smutná babička – sad grandmother

The pattern is: adjectives must match the noun in gender, number, and case.

Why is it dědeček není smutný and not dědeček je ne-smutný or dědeček není šťastný?

A few points here:

Není smutný is the normal, natural way to say is not sad.
- ne-smutný as a hyphenated word is not used in Czech.
- You almost never negate adjectives by putting ne- on the adjective if there is a form with ne- that already exists as a word (like šťastný / nešťastný).
Není smutný vs není šťastný:
- není smutný = he is not sad (maybe neutral, content, or happy)
- není šťastný = he is not happy (he might be sad, disappointed, etc.)
You could also say:
- … je moje babička šťastná a dědeček také.
  …my grandmother is happy and my grandfather too.
- Or … a dědeček je taky šťastný.

The author here simply chose a slightly different, more nuanced statement for the grandfather: he is at least not sad.

Could we leave out moje and just say babička je šťastná?

Yes, you can say:

Když je celá rodina doma, je babička šťastná a dědeček není smutný.

This would normally be understood as my/our grandmother from context.

Czech often omits possessives when the relationship is obvious (family members, body parts, etc.), especially if the owner is the subject or is clear from the situation:

Bolí mě hlava. – My head hurts. (no moje)
Babička je šťastná. – Grandma is happy. (probably “our/my” grandmother)

Adding moje just makes the relationship explicit, and may sound slightly more personal or emphatic.

Why are there no words like “the” or “a” in the Czech sentence?

Czech does not have articles. There is no direct equivalent of the or a/an.

So:

celá rodina can mean the whole family or a whole family, depending on context.
moje babička means my grandmother; you do not need the in front of it.

Czech usually relies on word order, context, and sometimes demonstratives like ten / ta / to to express ideas that English shows with articles:

ta rodina – that family / the family (in a more specific sense)
je celá rodina doma? – is the whole family at home?

How do you pronounce difficult words like šťastná and dědeček?

A rough approximation in English sounds (not perfect, but helpful):

šťastná ≈ “shtyast-nah”
- š like English sh
- ť is a soft t, a bit like t in student when said softly
- the á is long: aa sound, held longer
dědeček ≈ “dye-de-chek”
- ďe is a soft sound, something like dje or dye
- č like ch in church
- stress is always on the first syllable in Czech: ŠŤAS-tná, ĎE-de-ček

Czech spelling is very regular, so once you learn the sound values of š, ť, ď, č, á, é etc., you can reliably pronounce most words.