"Duzi chłopcy i mali chłopcy."

Translation: The big boys and little boys.

[JackHolmes3]

The audio in this one is very hard to make out

[BarboraHla2]

Is it not dużi chłopcy? according to this ż in duże changes to z in plural, I am seeing this change for the first time, can someone confirm?

[alik1989]

As far as grammar is concerned, the only thing that changes, is the ending, which becomes -i. The rest is just phonology and spelling conventions. In Polish, "i" is an palatalizing (softening) vowel, which means that it softens at least one preceding consonant. So in this case, ż is being softened to ź. Furthermore, spelling convention dictates that ź,ć and ś are written without the diacritical mark, when followed by the letter i. This why it's duzi, but the z is still pronounced as ź.

Here you'll find some more rules in the comments.

[BarboraHla2]

this makes perfect sense, thank you!

[zittler]

This was super clear! Dziękuje!

[Katrionapersson]

Is small not the same as little- mali chłopcy?

[Jellei]

Less idiomatic here, I think, but also correct.