Scribendo in commentario et verba difficilia in margine ponendo, Lucia verba nova memoria tenet.

They are gerunds from scribere and ponere.

A gerund is a verbal noun. In this sentence, both are in the ablative singular, and they express means or manner:

• scribendo = by writing / through writing
• ponendo = by putting / by placing

So the sentence begins by telling us how Lucia keeps the new words in memory.

Because Latin is packaging those actions as the method by which the main action happens.

The main clause is:

• Lucia ... verba nova memoria tenet = Lucia keeps new words in memory

The gerunds add the idea:

• by writing in her notebook
• and by putting difficult words in the margin

So instead of saying something like Lucia writes ... and puts ... and in this way remembers, Latin uses a more compact structure.

It can suggest both, depending on context.

With an ablative gerund, English may translate it as:

• by writing
• through writing
• while writing

Here the strongest idea is probably means: Lucia remembers new words by doing these things. But while writing is not a bad way to feel the Latin either.

Lucia is.

A gerund does not have its own separate subject. So in a sentence like this, the understood doer of scribendo and ponendo is the same as the subject of the main verb, which is Lucia.

So the sense is:

• Lucia, by writing ...
• Lucia, by putting ...

not someone else.

Because the sentence talks about two different sets of words.

• verba difficilia goes with ponendo
  = putting difficult words in the margin

• verba nova goes with tenet
  = keeping new words in memory

So the structure is:

• scribendo in commentario
• et verba difficilia in margine ponendo
• Lucia verba nova memoria tenet

A learner may first think both verba belong to the same part of the sentence, but they do not.

Because they agree with verba.

Verbum is a neuter noun. Its plural nominative and accusative form is verba. Since both nova and difficilia describe verba, they must match it in:

• gender: neuter
• number: plural
• case: accusative here

So:

• verba nova = new words
• verba difficilia = difficult words

The -a ending here is the normal neuter plural ending.

Because in + ablative usually shows location.

So:

• in commentario = in the notebook
• in margine = in/on the margin

This is the basic contrast learners are usually taught:

• in + ablative = in/on a place
• in + accusative = into/toward a place

Here the sentence focuses on where the writing is found, not on movement toward a place.

Also, commentarius in Latin can mean something like notebook, notes, or commentary, depending on context. Here notebook makes best sense.

Yes. Here ponendo is understood with the object verba difficilia.

That said, this is also a place where students often hear about the gerundive alternative. Latin often prefers to avoid a gerund with a direct object, especially in more classical style, and may instead use a gerundive construction.

So alongside verba difficilia in margine ponendo, you may also encounter a more classically styled expression such as:

• verbis difficilibus in margine ponendis

For a learner, the important point is this: in the sentence as given, ponendo clearly means putting/placing, and verba difficilia is what is being put there.

Lucia is nominative singular, the subject of tenet.

It comes after the opening gerund phrase because Latin word order is flexible. The sentence begins with the method first:

• Scribendo ... et ... ponendo = by writing ... and by putting ...

and only then gives the subject and main statement:

• Lucia verba nova memoria tenet

This is very normal Latin style. English usually prefers to introduce the subject earlier, but Latin often moves things around for emphasis or flow.

Literally, it means holds in memory or keeps in memory.

This is a common Latin way to express the idea that English often gives with a single verb:

• remember
• keep in mind

So verba nova memoria tenet is not a strange literal image in Latin; it is a normal idiomatic expression.

Because the idiom is memoria tenere with memoria in the ablative.

So Latin says, in effect:

• to hold something in memory

rather than using memoria as a direct object.

This is one of those expressions that is best learned as a set phrase:

• aliquid memoria tenere = to remember something

Yes, to a large extent.

Because Latin marks grammatical relationships mostly through endings, not fixed word order, the sentence could be rearranged in various ways without changing the basic meaning.

What would stay the same is the grammar:

• Lucia remains the subject
• verba nova remains the object of tenet
• verba difficilia remains connected with ponendo
• in commentario and in margine remain prepositional phrases
• scribendo and ponendo remain the means/manner phrases

The exact order used here is natural because it foregrounds how Lucia learns before stating what she achieves.