Learn Hardcore Ukrainian: Петро працює як вчитель.

The sentence is composed of three parts: the subject Петро (Petro), the verb працює (works), and the complement як вчитель (as a teacher). This order is a straightforward Subject-Verb-Complement structure.

What does the verb працює mean and how is it formed?

Працює is the third-person singular present tense form of the verb працювати, which means to work. It is conjugated to agree with the subject Петро.

What role does the word як play in this sentence?

In this context, як means as. It is used to indicate the capacity or role in which Petro is working—that is, he is working in the capacity of a teacher.

Why is вчитель used in its base (nominative) form instead of changing to the instrumental case?

When using the construction with як to express the role or occupation, the noun following it typically remains in the nominative case. Therefore, вчитель stays in its base form. In contrast, without як, one might use the instrumental case (e.g., працює вчителем) to denote occupation.

Is there any difference in meaning between "Петро працює як вчитель" and "Петро працює вчителем"?

Both sentences convey that Petro works as a teacher. The version with як explicitly introduces his role, which can emphasize the function he serves, while the instrumental case version is more of a direct statement of his occupation. The nuance is subtle, and in everyday speech they are often interchangeable.