Learn Hardcore Turkish: Onun not alması toplantıyı çok hızlandırdı. - Her taking notes sped up the meeting a lot.

Because the verb phrase is being turned into a noun so it can be the subject of the sentence. Turkish uses the verbal-noun suffix -mA plus a possessive ending to nominalize verbs:

al- (take) + -ma (verbal noun) + -sı (3sg possessive) → alması = “his/her taking” So Onun not alması = “his/her taking notes” functioning as a noun phrase (the subject).

What does Onun do here? Why not just O?

In nominalized clauses, the “subject” of the verbal noun is marked with genitive case, and the verbal noun itself takes a possessive suffix. This is the genitive–possessive construction:

Onun (genitive of “o”) + alması (3sg possessed verbal noun) Using bare o is ungrammatical in this structure; it must be onun.

Can I drop onun and just say Not alması toplantıyı çok hızlandırdı?

Yes, if the possessor is clear from context. The suffix -sı on alması already encodes a 3rd person possessor. Without onun, it will read as “his/her/its taking notes…” with the possessor understood from context. If there’s no context, omitting onun can be ambiguous.

What is the -s- in alması?

It’s a buffer consonant. When the verbal-noun -mA is followed by a 3rd-person possessive suffix, Turkish inserts -s-: al-ma-s-ı. Without it, the vowels would clash.

Why is toplantıyı in the accusative?

Because it’s the direct object of the transitive verb hızlandırmak (“to speed up [something]”). Turkish marks specific/definite direct objects with the accusative -(y)I. Here the meeting is a specific one, so toplantı → toplantıyı.

Could I say toplantı hızlandı instead of toplantıyı hızlandırdı?

That would change the meaning and structure:

hızlandı = “(it) sped up” (intransitive; no object)
hızlandırdı = “(someone/something) sped (it) up” (causative, transitive) Your sentence attributes the cause to “his/her taking notes,” so you need the causative hızlandırdı with an object.

What does çok modify here, and where can it go?

Here çok modifies the verb: “sped up a lot.” The natural place is right before the verb: toplantıyı çok hızlandırdı. If you put çok before the object, e.g., çok toplantıyı hızlandırdı, it changes the meaning to “sped up many meetings.”

Can I change the word order, like Toplantıyı onun not alması çok hızlandırdı?

Yes. Turkish word order is flexible for focus and emphasis. Fronting toplantıyı or onun not alması highlights them, but the core relations don’t change because case/suffixes carry the grammar. A comma after the initial subject phrase is optional: Onun not alması, toplantıyı çok hızlandırdı adds a slight pause/emphasis.

Is not almak the most natural way to say “to take notes”? What about not tutmak?

Both are common and natural:

not almak = to take notes (very common)
not tutmak = to keep/take notes (slightly more idiomatic in some contexts) Your sentence works with either: Onun not tutması toplantıyı çok hızlandırdı is equally fine.

Does not almak also mean “to receive a grade”? Is the sentence ambiguous?

Yes, not can mean “note” or “grade,” and not almak can mean “to get a grade.” In your sentence, the presence of toplantı (“meeting”) strongly favors the “taking notes” reading; “getting a grade” wouldn’t fit the context.

Could I use a -DIK form, like Onun not aldığı?

Not for this meaning. -DIK forms relative clauses or more finite noun clauses tied to a complement (e.g., “the note that he took,” “that he took notes [as a fact that…]”). For a simple gerund-like subject (“his/her taking notes”), the -mA + possessive pattern (not alması) is the natural choice.

What about Onun not alışı with -ış/-iş?

-ış/-iş also nominalizes verbs but often conveys habitual manner or style. Onun not alışı would lean toward “his/her way of taking notes.” It’s possible but a bit more about manner; for a particular event causing the speed-up, not alması is more neutral/natural.

How do I say “my/your/their taking notes” with this pattern?

Use the possessor in genitive + the matching possessive suffix on the verbal noun:

Benim not almam (my taking notes)
Senin not alman (your taking notes)
Onun not alması (his/her/its taking notes)
Bizim not almamız (our taking notes)
Sizin not almanız (your [pl/formal] taking notes)
Onların not almaları (their taking notes)

What are the word-by-word formations here?

Onun = o (he/she/it) + -(n)un (genitive)
not = “note” (loanword), behaves like a regular noun for suffixes
alması = al- (take) + -ma (verbal noun) + -sı (3sg possessive)
toplantıyı = toplantı (meeting) + -y- (buffer) + -ı (accusative)
çok = very/much (adverb)
hızlandırdı = hız (speed) + -lan- (become) + -dır- (causative “make become”) + -dı (past) → “(he/she/it) sped [it] up”

Why are the suffix vowels like -ı in alması, toplantıyı, and hızlandırdı?

Vowel harmony. Suffix vowels harmonize with the last vowel of the stem:

al-ma-s-ı (last vowel a → back unrounded → ı)
toplantı-y-ı (last vowel ı → back unrounded → ı)
hızlandır-dı (last vowel ı → back unrounded → ı) Buffers -s- and -y- are added to prevent vowel clashes.

Is a comma needed after Onun not alması?

No. Normally there’s no comma between subject and predicate in Turkish. You might insert one for a rhetorical pause or emphasis, but it’s not required.

Could I rephrase with “thanks to,” using an intransitive verb?

Yes: Onun not alması sayesinde toplantı çok hızlandı. Here sayesinde (“thanks to”) is used, and the verb is intransitive hızlandı (“the meeting sped up”).

What’s the difference between hızlandırdı and hızlandırmış?

hızlandırdı (-DI past): plain past, typically direct knowledge.
hızlandırmış (-miş past): inferential/hearsay past; used when you didn’t witness it, are reporting, or want a softer/less assertive tone. Both can fit depending on what you want to convey.