Третий урок интересный.

The third lesson is interesting.

Breakdown of Третий урок интересный.

• интересный: interesting
• урок: the lesson
• третий: third

Questions & Answers about Третий урок интересный.

Why is there no verb in this sentence, like есть or является?

In Russian the present‐tense copula быть (“to be”) is normally omitted. So instead of saying Третий урок есть интересный or Третий урок является интересным, you simply say Третий урок интересный and the “is” is understood.

What case are третий, урок and интересный in?

All three words are masculine nominative singular.

• урок (lesson) is the subject of the sentence and takes the nominative.
• Both третий (ordinal number) and интересный (adjective) agree with урок in gender, number and case.

How do ordinal numbers like третий change form?

Ordinal numbers in Russian behave like adjectives: they have endings for gender, number and case. From the base cardinal number три:
• Masculine Nom. Sing. → третий
• Feminine Nom. Sing. → третья
• Neuter Nom. Sing. → третье
• Plural Nom. → третьи
And each of these will take the appropriate endings in other cases (e.g. третьего, третьему etc.).

Why is третий formed from три with a stem change, instead of just триный?

The first few ordinals in Russian are irregular.

• первый from один
• второй from два
• третий from три
  They change their stem (три → трет-) before adding the adjective endings. Later ordinals (четвёртый, пятый, etc.) are more regular.

Why does интересный come after урок rather than before it?

Here интересный functions as a predicate adjective (it describes the state of the subject). Predicative adjectives follow the noun they describe:
Третий урок (subject) + интересный (predicate).
If you move интересный before урок, it becomes attributive: интересный урок meaning “an interesting lesson,” not “the lesson is interesting.”

Could I use the short-form adjective интересен instead of интересный?

Yes. Russian has two predicative adjective forms:

• Full form: Третий урок интересный (common in speech)
• Short form: Третий урок интересен (more formal or emphasising the result/state)

Why can’t I say Третий урок интересно?

интересно is either an adverb (“interestingly”) or the neuter short‐form adjective. Since урок is masculine, the correct short‐form predicative is интересен, not интересно.

Why are there no articles like the or a?

Russian does not use indefinite or definite articles. Context or word choice (e.g. ordinals like третий) conveys definiteness. Here третий already signals “the third,” so no separate article is needed.

How do I pronounce Третий урок интересный? Where are the stresses?

The stress pattern is:
• Тре́тий (on ТРЕ)
• уро́к (on РОК)
• интере́сный (on РЕС)
Pronounce roughly as “TRE-tee u-ROK in-te-RES-nyi.”