Questions & Answers about Это обязательный урок.
Russian makes a clear distinction between:
Это + noun
- Functions like “this is / it is”.
- Used to identify or classify something.
- Это обязательный урок. = This is a mandatory lesson. / It’s a mandatory lesson.
Этот + noun
- Means “this [specific] …” and directly modifies the noun.
- Этот урок обязательный. = This lesson is mandatory.
- Here этот is just a determiner (“this”), not “this is”.
Он
- Refers back to a masculine noun already mentioned (like урок).
- You can say: Урок обязательный. Он обязательный. = The lesson is mandatory. It is mandatory.
- But Он обязательный урок is wrong: Russian does not do “He is a mandatory lesson” the way English might say “He is a teacher.”
So in Это обязательный урок, это is not “this lesson” grammatically; it’s “this/it” used in the pattern “this is X”.