Learn Hardcore Russian: Их родители, кажется, тоже считают этот урок полезным. - It seems their parents also consider this lesson useful.

кажется here is a parenthetical word (вводное слово) meaning “it seems.” In Russian, вводные слова are normally set off by commas, just as in English you’d say “Their parents, it seems, also…” The commas show that кажется is an aside, not part of the main clause structure.

What part of speech is кажется, and does it change form?

кажется is the 3rd-person-singular present tense of the impersonal verb казаться (“to seem”). It doesn’t agree with a subject—you always use кажется when you mean “it seems.” Other forms include past tense казалось (“it seemed”) and perfective future (по)кажется in contexts like “it will appear.”

Why does считают take этот урок in the accusative and полезным in the instrumental?

The verb считать (“to consider”) in Russian uses a two-part complement: • a direct object in the accusative (what is being considered), here этот урок
• a predicative adjective or noun in the instrumental (how it is considered), here полезным
So the pattern is считать + Accusative + Instrumental.

Why is полезным in the Instrumental case instead of Nominative?

Because it’s the predicate complement of считать. In Russian, when you describe what you consider something to be, the descriptive word goes in the instrumental:
– Они считают этот урок полезным.
If you used nominative (полезный), it would break this rule and sound ungrammatical in standard Russian.

What is the function of тоже in this sentence, and why is it placed before считают?

тоже means “also” or “too.” Here it indicates that, in addition to others (perhaps you or someone else), their parents share the same opinion. Placing тоже before считают emphasizes that the parents also perform the action of considering. You could move тоже slightly (e.g. after родители or before кажется), but the meaning stays “also.”

Can кажется be placed elsewhere in the sentence?

Yes. As a parenthetical, кажется is quite mobile. You could say:
• Кажется, их родители тоже считают этот урок полезным.
• Их родители тоже, кажется, считают этот урок полезным.
All variants are grammatically correct; you only adjust comma placement accordingly.

What are some synonyms for кажется, and do they differ in usage?

Common synonyms include:
• похоже (informal “it appears/looks like”)
• по-видимому (neutral “apparently”)
• вероятно (formal “probably”)
Nuance: похоже is more colloquial and visual (“it looks like”), по-видимому is neutral and slightly more formal, вероятно expresses probability rather than mere appearance.

Could we replace считать with думать in this sentence?

Not directly. думать (“to think”) typically requires a subordinate clause:
• Их родители думают, что этот урок полезен.
You can’t say Их родители думают этот урок полезным. If you want the structure Accusative + Instrumental, you need считать, называть, or a similar verb of judgment.

Why is их used for “their,” and is ихние acceptable?

их is the standard genitive/possessive pronoun for “their.” It doesn’t change for gender or number. ихние is a non-standard, colloquial variant found in some dialects or casual speech but is considered incorrect in literary or formal Russian.

Why is этот used before урок—could you omit it?

этот is a demonstrative pronoun meaning “this,” specifying which lesson you’re talking about. Omitting этот would leave the phrase general (“Their parents consider a lesson useful,” which is awkward). If you mean “this particular lesson,” you need этот урок to point it out.