Kiedy dzieci są zmęczone, mówię: „Umyjcie ręce, umyjcie zęby i chodźcie spać”.

Kiedy means when.

It introduces a time clause: Kiedy dzieci są zmęczone = When the children are tired.

Polish often puts this kind of clause at the beginning, just like English can. You could also reorder the sentence:

Mówię: ... , kiedy dzieci są zmęczone.

But starting with Kiedy... sounds very natural here.

Dzieci is plural. It is the plural of dziecko = child.

So:

• dziecko = child
• dzieci = children

It is an irregular plural, so you just have to learn it as a whole form.

Because dzieci is plural.

Polish verb forms must agree with the subject:

• dziecko jest zmęczone = the child is tired
• dzieci są zmęczone = the children are tired

So są is the correct present-tense form of być for a plural subject.

Because dzieci takes the non-masculine-personal plural agreement form in Polish.

That means adjectives with dzieci are usually like this:

• małe dzieci
• zmęczone dzieci
• dzieci są zmęczone

Even though children are people, the noun dzieci does not behave like a masculine-personal plural noun such as chłopcy.

Compare:

• Chłopcy są zmęczeni = The boys are tired
• Dzieci są zmęczone = The children are tired

Mówię is the 1st person singular present tense of mówić = to say / to speak.

So mówię means I say or I am saying, depending on context.

In this sentence, it has a habitual meaning:

When the children are tired, I say...

So it does not mean only one specific moment. It means this is what the speaker typically says in that situation.

The comma is there because Kiedy dzieci są zmęczone is a subordinate clause. In Polish, a clause introduced by kiedy is normally separated by a comma.

The colon after mówię introduces direct speech:

mówię: ...

So the structure is:

• time clause
• main clause
• direct quotation

This is very standard punctuation in Polish.

Because they are commands addressed to more than one person.

The ending -cie is a common marker of the 2nd person plural imperative.

Compare:

• umyj = wash! (to one person)

• umyjcie = wash! (to more than one person)

• chodź = come on! / come!
• chodźcie = come on! (to more than one person)

Since the speaker is talking to children in the plural, the plural imperative is needed.

This is mainly about aspect.

• myć is imperfective
• umyć is perfective

In commands, Polish often uses the perfective when the speaker wants one complete action:

• Umyjcie ręce = Wash your hands completely / go wash your hands
• Umyjcie zęby = Brush/wash your teeth

This sounds natural for a bedtime routine, where the speaker wants the actions done once and completed.

By contrast, myjcie often sounds more like:

• a general instruction
• a repeated/habitual action
• focus on the process rather than completion

For example:

Myjcie ręce przed jedzeniem = Wash your hands before eating

Because Polish often leaves out possessive words like your, my, his, etc. when they are obvious from context, especially with body parts.

So Polish naturally says:

• umyj ręce = wash your hands
• umyj zęby = brush your teeth
• boli mnie głowa = my head hurts

Adding a possessive is possible, but usually unnecessary unless you want emphasis or contrast.

They are in the accusative, because they are the direct objects of the verb.

• umyć ręce = to wash hands
• umyć zęby = to brush/wash teeth

In these plural forms, the accusative happens to look the same as the nominative:

• ręce
• zęby

So even though the form does not change visibly here, the function is still accusative.

Both are possible, but they are not exactly the same in tone.

• idźcie spać = go to sleep / go to bed
• chodźcie spać = come on, off to bed / come sleep now

Chodźcie is often used in a more inviting, guiding, or parent-like way, especially with children. It can sound softer or more natural in family speech.

So in this sentence, chodźcie spać fits very well because the speaker is addressing children directly.

Repeating the verb makes the sequence of actions clearer and more natural:

• Umyjcie ręce, umyjcie zęby i chodźcie spać

This sounds like a list of bedtime instructions.

Polish can sometimes omit repeated verbs, but in commands like this, repetition is very common because it gives each action its own emphasis and makes the order easy to follow.