Learn Russian: Моя сестра много работает, чтобы заработать деньги на отпуск. - My sister works a lot in order to earn money for a vacation.

In English, we often just use an infinitive to show purpose, like "works to earn." In Russian, to say "in order to do something" you must use чтобы followed by the infinitive.

Is the comma before чтобы always required?

Yes! Russian punctuation rules are strict about separating clauses. You must always put a comma before a subordinate clause starting with words like чтобы, что, or потому что.

What is the difference between работает and заработать?

Работает is an imperfective verb meaning "works" (an ongoing, habitual action). Заработать is a perfective verb meaning "to earn" (focusing on the successful result). Adding the prefix за- changes the focus from the ongoing process of working to the final result of earning.

Why do we use на отпуск instead of для отпуска for "for a vacation"?

While для usually means "for," Russian uses the preposition на followed by the Accusative case when talking about spending, saving, or earning money for a specific purpose or event.

What case is in this sentence?