Учитель начинает урок.

the teacher

Breakdown of Учитель начинает урок.

• урок: the lesson
• начинать: to start

Questions & Answers about Учитель начинает урок.

What is the grammatical role and case of Учитель in this sentence?

Учитель is a noun in the nominative case. It functions as the subject of the sentence, meaning “the teacher” is performing the action.

What is the role and case of урок here?

урок is a noun in the accusative case, serving as the direct object of the verb. Since урок is inanimate, its accusative form is identical to its nominative form.

Why isn’t there any article before Учитель or урок?

Russian does not use articles (like “the” or “a/an” in English). Context tells you whether you mean something definite or indefinite.

What tense and aspect is начинает?

начинает is present tense, third-person singular of the imperfective verb начинать (“to begin” or “to start”). Imperfective verbs describe ongoing, repeated, or habitual actions.

Could you show the full present-tense conjugation of начинать?

Sure:
я начинаю – I begin
ты начинаешь – you (sing.) begin
он/она начинает – he/she begins
мы начинаем – we begin
вы начинаете – you (pl. or formal) begin
они начинают – they begin