Κατά τη γνώμη μου, αυτό το μάθημα είναι πολύ χρήσιμο.

In my opinion, this lesson is very useful.

Breakdown of Κατά τη γνώμη μου, αυτό το μάθημα είναι πολύ χρήσιμο.

• είμαι: to be
• αυτός: this
• πολύ: very
• το μάθημα: the lesson
• χρήσιμος: useful
• κατά τη γνώμη μου: in my opinion

Questions & Answers about Κατά τη γνώμη μου, αυτό το μάθημα είναι πολύ χρήσιμο.

What exactly does Κατά mean in Κατά τη γνώμη μου? Is this a fixed expression?

In this sentence, Κατά is a preposition meaning according to.

Κατά τη γνώμη μου literally means according to my opinion, and it functions just like English in my opinion.

It is effectively a fixed expression:

• Κατά τη γνώμη μου = in my opinion
• You will also see κατά τη γνώμη σου / του / της / μας / σας / τους for other persons.

You cannot replace Κατά here with something like Στη (which would mean in the opinion, and is not idiomatic) if you want the same nuance. The natural phrase for in my opinion is Κατά τη γνώμη μου or simply Κατά τη γνώμη μου, ... at the start of a sentence.

Why is it τη γνώμη and not την γνώμη?

The full form of the feminine singular accusative article is την.
Modern Greek often drops the final -ν when the next word starts with certain consonants.

General rule (informal but useful):

• Keep -ν before: κ, π, τ, ξ, ψ, γκ, μπ, ντ, τσ, τζ, και vowels.
• Drop -ν before most other consonants.

Γνώμη starts with γν-, so in everyday writing and speech people usually drop the -ν:

• τη γνώμη (more common) but την γνώμη is not wrong; it’s just more formal or careful style.

So:

• τη γνώμη μου and την γνώμη μου are both grammatically correct; you’ll mostly see τη γνώμη μου.

Why is it τη γνώμη (accusative) and not της γνώμης (genitive) to say my opinion?

In Greek, possession with nouns like opinion is usually expressed with a possessive pronoun rather than a genitive noun phrase.

• η γνώμη μου = my opinion
  (literally: the opinion my)
• της γνώμης μου would be something like of my opinion, and is much less common and sounds heavier or more formal, used in different contexts.

In your sentence:

• Κατά τη γνώμη μου = According to my opinion
  • τη γνώμη: accusative, because it is the object of the preposition κατά
  • μου: enclitic possessive pronoun meaning my

So the structure is:

• κατά
  • τη γνώμη (accusative object of the preposition) + μου (possessor)

Can I move Κατά τη γνώμη μου to a different place in the sentence?

Yes, Greek word order is flexible. Some common options:

1. Κατά τη γνώμη μου, αυτό το μάθημα είναι πολύ χρήσιμο.
   Very natural; the phrase at the start emphasizes that what follows is just your opinion.

2. Αυτό το μάθημα, κατά τη γνώμη μου, είναι πολύ χρήσιμο.
   Slightly more contrastive: this particular course, in my opinion, is very useful.

3. Αυτό το μάθημα είναι, κατά τη γνώμη μου, πολύ χρήσιμο.
   Emphasizes πολύ χρήσιμο while still marking it as your opinion.

4. Αυτό το μάθημα είναι πολύ χρήσιμο, κατά τη γνώμη μου.
   Similar to English this course is very useful, in my opinion; a bit more informal/conversational.

All are grammatical; the differences are about emphasis and style, not correctness.

Why is it αυτό το μάθημα and not something like αυτή η μάθημα?

Because μάθημα is a neuter noun in Greek.

• μάθημα: neuter, singular
• The demonstrative αυτό is the neuter form of this
• The article το is also neuter singular

So everything agrees in gender, number, and case:

• αυτό (this, neuter nominative singular)
• το (the, neuter nominative singular)
• μάθημα (lesson/class, neuter nominative singular)

If the noun were feminine, you would use:

• αυτή η τάξη = this class (as in the group of students or the classroom session)
  • τάξη is feminine; thus αυτή and η

Here, we are talking about a course/lesson in the abstract sense, so μάθημα is the right word, and it is neuter.

What is the difference between αυτό το μάθημα and just το μάθημα?

• το μάθημα = the lesson / the course
• αυτό το μάθημα = this lesson / this course

Adding αυτό specifies which lesson you mean, pointing to something close, in context or physically near.

So:

• Το μάθημα είναι πολύ χρήσιμο.
  Could be any previously mentioned lesson.
• Αυτό το μάθημα είναι πολύ χρήσιμο.
  Emphasizes this particular lesson (not another one).

Why is it πολύ χρήσιμο and not πολύ χρήσιμη or πολλή χρήσιμη?

The adjective must agree with the noun μάθημα, which is neuter singular.

• χρήσιμος, χρήσιμη, χρήσιμο = useful
  
  • masculine: χρήσιμος
  • feminine: χρήσιμη
  • neuter: χρήσιμο

Since μάθημα is neuter:

• μάθημα χρήσιμο = useful lesson
• With αυτό το: αυτό το μάθημα είναι πολύ χρήσιμο.

As for πολύ:

• Here πολύ is an adverb meaning very, so it is invariable:
  • πολύ χρήσιμο (neuter)
  • πολύ χρήσιμη (feminine)
  • πολύ χρήσιμος (masculine) In all cases πολύ stays the same because adverbs do not change for gender or number.

The form πολλή is a feminine adjective (e.g. πολλή δουλειά = a lot of work), not appropriate here.

Is there any difference between πολύ χρήσιμο and πάρα πολύ χρήσιμο?

Yes, it is a difference in intensity:

• πολύ χρήσιμο = very useful
• πάρα πολύ χρήσιμο = extremely / really very useful

πάρα πολύ just adds extra emphasis, like so very or really very in English.

You could also say:

• αρκετά χρήσιμο = quite useful
• λίγο χρήσιμο (rare, more often όχι και τόσο χρήσιμο) = not that useful

Why is there a comma after μου?

The comma separates the introductory phrase Κατά τη γνώμη μου from the main clause αυτό το μάθημα είναι πολύ χρήσιμο.

This is very similar to English:

• In my opinion, this course is very useful.

In Greek, short introductory adverbial phrases like:

• Κατά τη γνώμη μου
• Γενικά
• Συνήθως are often followed by a comma when they stand at the beginning of the sentence, to make the sentence easier to read.

So:

• Κατά τη γνώμη μου, αυτό το μάθημα είναι πολύ χρήσιμο.
  is standard punctuation.

What is the role of είναι here? Could it be omitted?

Είναι is the 3rd person singular of the verb είμαι (to be).

• αυτό το μάθημα = this course (subject)
• είναι = is
• πολύ χρήσιμο = very useful (predicate)

So the structure mirrors English:

• This course is very useful.

In standard Greek, you cannot omit είναι in this type of sentence. You need the verb to be to link the subject to the adjective:

• ✗ Αυτό το μάθημα πολύ χρήσιμο.
  sounds incorrect or at least incomplete.

How do you pronounce γνώμη and χρήσιμο?

Approximate pronunciation (in simple English phonetics):

• γνώμη: GNO-mee

  • γν together is like gn in gnostic (with a hard, voiced gh sound)
  • Stress on the first syllable: ΓΝΩμη

• χρήσιμο: HREE-see-mo

  • χ is a voiceless sound from the back of the throat (like the ch in German Bach or Scottish loch)
  • η sounds like ee
  • Stress on the first syllable: ΧΡΗσιμο

More precise (IPA):

• γνώμη = /ˈɣnɔ.mi/ (or /ˈɣno.mi/ in modern pronunciation)
• χρήσιμο = /ˈxri.si.mo/

Could I say Σύμφωνα με τη γνώμη μου instead of Κατά τη γνώμη μου?

You could, but it sounds awkward and redundant.

• σύμφωνα με already means according to
• τη γνώμη μου means my opinion

So σύμφωνα με τη γνώμη μου is like according to my opinion, which is technically understandable but feels clumsy.

More natural options:

• Κατά τη γνώμη μου, ... = In my opinion, ...
• Σύμφωνα με μένα, ... = According to me, ...
• Κατά τη δική μου γνώμη, ... = according to my own opinion (more emphatic)

For everyday speech, Κατά τη γνώμη μου or simply Νομίζω ότι... (I think that...) are the best choices.