Mentre pulisco la cucina, mi metto a controllare se qualche piastrella si muove.

Mentre means while. It introduces an action that is happening at the same time as another one.

In this sentence:

• Mentre pulisco la cucina = While I’m cleaning the kitchen
• mi metto a controllare... = I start checking...

So mentre sets the background action, and the main clause tells you what starts happening during that time.

In Italian, the simple present tense is often used where English would prefer am/is/are + -ing.

So:

• pulisco la cucina can mean I clean the kitchen or I’m cleaning the kitchen, depending on context.
• Because mentre already makes the ongoing meaning clear, pulisco sounds very natural here.

You could say Mentre sto pulendo la cucina..., but it is not necessary. The version with pulisco is more straightforward and very common.

Mettersi a + infinitive means to start/begin doing something.

So:

• mi metto a controllare = I start checking
• more literally, I put myself to checking

It often suggests that someone suddenly or deliberately begins an action.

Examples:

• Mi metto a studiare. = I start studying.
• Si mette a ridere. = He/She starts laughing.

Here it gives the idea that, while cleaning, the speaker begins checking the tiles.

Because mettersi a + infinitive is a fixed pronominal expression.

• mettere by itself usually means to put
• mettersi a fare qualcosa means to start doing something

So the mi is not really to myself in a literal English sense; it is part of the expression.

Compare:

• Metto il libro sul tavolo. = I put the book on the table.
• Mi metto a leggere. = I start reading.

Because the pattern is:

mettersi a + infinitive

So after mettersi, Italian uses a before the next verb.

Examples:

• Mi metto a lavorare. = I start working.
• Si mette a cantare. = She starts singing.

You just need to learn this as the normal construction.

Because se here means whether/if in an indirect question.

• controllare se qualche piastrella si muove = to check whether any tile moves / is loose

Italian often uses se after verbs like:

• vedere se = see if
• controllare se = check if
• sapere se = know whether
• chiedere se = ask whether

This is not the same se as if in conditional sentences like If it rains...

Because qualche is followed by a singular noun, even though its meaning is plural-like.

So:

• qualche piastrella = some tiles / a few tiles
• not qualche piastrelle

This is a very common point for learners.

Other examples:

• qualche minuto = a few minutes
• qualche amico = a few friends

Grammatically singular, but semantically it refers to more than one.

Because qualche piastrella is grammatically singular, so the verb agrees in the singular:

• qualche piastrella si muove

Even though the meaning may be some tile(s), the grammar is singular.

That said, the sentence can also be understood as checking whether any individual tile is loose or moving.

Here si muove means something like:

• moves
• shifts
• comes loose
• wobbles

With a tile, this usually suggests that it is not firmly fixed.

The verb muoversi often means to move in an intransitive sense:

• La sedia si muove. = The chair moves / is wobbling.
• Il dente si muove. = The tooth is loose.

So in this sentence, si muove is very natural for a tile that may be loose.

It looks reflexive, but it is better to think of muoversi here as the normal intransitive form meaning to move.

It is not really the same as saying the tile is actively doing something to itself. Italian often uses this -si form in verbs describing movement or change of state.

So for a learner, the best approach is:

• learn muovere = to move something
• learn muoversi = to move

Examples:

• Muovo il tavolo. = I move the table.
• Il tavolo si muove. = The table moves / is unstable.

Because se here introduces an indirect yes/no question, and in that case Italian normally uses the indicative, not the subjunctive.

So:

• controllare se qualche piastrella si muove = correct

This is like:

• Non so se viene. = I don’t know if he’s coming.
• Vediamo se funziona. = Let’s see if it works.

The subjunctive is not required here.

Yes, but the meaning would change.

• se qualche piastrella si muove = whether any tile / some tiles are loose
• se una piastrella si muove = whether one tile is moving / whether a tile is moving

Qualche gives a broader sense: the speaker is checking around to see if there are any loose tiles at all.

There is a small but useful difference:

• controllo = I check / I’m checking
• mi metto a controllare = I start checking

The version with mi metto a emphasizes the beginning of the action. It can suggest that this was not the main activity at first, but then the speaker starts doing it.

So the sentence feels a bit like: While cleaning the kitchen, I end up starting to check whether any tiles are loose.

It is very normal and helpful here.

• Mentre pulisco la cucina, mi metto a controllare...

The first clause is an introductory subordinate clause, so the comma makes the sentence easier to read. In informal writing, punctuation can vary, but this comma is perfectly standard.

Not exactly, or at least the nuance would change.

• mentre = while, emphasizing simultaneity
• quando = when, often referring more generally to the moment something happens

So:

• Mentre pulisco la cucina... = While I’m cleaning the kitchen...
• Quando pulisco la cucina... could sound more like When I clean the kitchen... or Whenever I clean the kitchen...

In this sentence, mentre is the better choice because the two actions are happening at the same time.

Piastrella means tile.

In a kitchen, it could refer to:

• a floor tile
• a wall tile

The sentence itself does not specify which kind. The important idea is that the speaker is checking whether any tile is loose or shifting.