"Biorę kawałek mydła."

Translation: I am taking a piece of soap.

[icha1221]

Can you say a piece of soap? (I don't speak english fluently)

[Jellei]

Well, what you would buy in a store is "a bar of soap" (kostka mydła), but when you use some of it and perhaps even break a part of it, you could say that it's a piece of soap.

[wiktorka234]

Czy "kawałek" może też oznaczać cząstkę układanki?

[Okcydent]

Tak. Ogólnie tak. Choć jeśli mamy do czynienia z puzlami to pojedynczy element nazywamy puzlem.

[idanlipin]

Just don't drop it!

[Euhan1]

Why isn't "bar" accepted? I can't see what would be a bit of soap but not qualify as a bar of soap.

[Jellei]

"kawałek" isn't idiomatic. It must be literally "a piece" of soap. "a bar of soap" that you buy in a shop is "kostka mydła".