Learn Hardcore Finnish: Ehkä syön puuroa aamulla. - Maybe I will eat porridge in the morning.

Because puuroa is the partitive singular, used for an indefinite amount of a mass noun after verbs like “eat.” It corresponds to English “some porridge.”

Syön puuroa = I eat some porridge / I’m eating porridge (unspecified amount).
Syön puuron (genitive “total object”) = I’ll eat the porridge / a whole portion (a specific, complete serving).
Puuro (nominative) would be a subject form: Puuro on hyvää “Porridge is good.”

What exactly does aamulla mean, and how is it different from aamuisin or aamuna?

aamulla (adessive) = “in the morning” (on the morning of the relevant day; not inherently habitual).
aamuisin = “in the mornings” (habitual, regularly).
aamuna (essive with a specifier) = “on (a particular) morning,” often with a modifier: Jouluaamuna “on Christmas morning,” Eräänä aamuna “one morning.”

Where can I put ehkä in the sentence, and does word order change the meaning?

Finnish word order is flexible and mostly affects focus:

Neutral/common: Ehkä syön puuroa aamulla.
Equally common: Syön ehkä puuroa aamulla.
Focus on time: Aamulla ehkä syön puuroa.
Focus on what you’ll eat (contrastive): Ehkä puuroa syön aamulla. All mean roughly the same; moving ehkä shifts emphasis rather than grammar.

Does this sentence talk about the future? Finnish seems not to have a future tense.

Right: Finnish uses the present for future time. Ehkä syön puuroa aamulla can mean “Maybe I’ll eat porridge in the morning.” If you want to show intention or degree of certainty:

Intention: Aion syödä puuroa aamulla (I intend to eat…).
Possibility: Saatan syödä puuroa aamulla (I might eat…).

Why is there no word for “I”?

The verb ending marks the person. Syön already means “I eat.” You can add minä for emphasis or contrast: Ehkä minä syön… (“Maybe I will (as opposed to someone else)”).

How do I say “Maybe I won’t eat porridge in the morning”?

Use the negative verb plus the connegative main verb:

Ehkä en syö puuroa aamulla. Notes:
The negative carries the person (en = I don’t).
The main verb is syö (no personal ending).
The object stays partitive (puuroa).

What case is aamulla, and when do you use it for time?

Aamulla is adessive (-lla/-llä). It’s commonly used for time expressions meaning “at/on”:

yöllä (at night), päivällä (during the day), illalla (in the evening), kesällä (in summer). It’s the default for broad parts of the day and some seasons.

What is the verb form syön exactly?

Dictionary form: syödä (to eat).
syön = 1st person singular, present indicative.
Other forms: syöt (you eat), syö (he/she eats), past söin (I ate), negative en syö (I don’t eat).

Any pronunciation tips for ehkä syön puuroa aamulla?

y (in syön) is a front rounded vowel (like French “u” in “tu”).
ö (in syön) is like German “ö” (or English “er” in “her” but rounded).
Double letters are long: aa in aamulla, ll in aamulla.
ä (in ehkä) is like “a” in “cat,” but fronted.
Pronounce hk in ehkä clearly as two sounds: h+k.

Can I say “for breakfast” instead of “in the morning”?

Yes:

Ehkä syön puuroa aamiaiseksi. (for breakfast; more formal/standard)
Ehkä syön puuroa aamupalaksi. (for breakfast; colloquial/common) You can also say Syön aamupuuroa (“I eat breakfast porridge”).

How would I turn this into a yes/no question?

Use the question clitic -ko/-kö on the verb:

Syönkö puuroa aamulla? (Will/Do I eat porridge in the morning?) You typically don’t use ehkä in a plain yes/no question. Rhetorical Ehkäkö…? exists but is stylistically marked. Note vowel harmony: -kö after front vowels (syönkö).

Are there alternatives to ehkä with different nuances?

kai = “I suppose/maybe” (colloquial, the speaker tentatively assumes something): Kai syön puuroa aamulla.
varmaan/varmasti = probably/certainly (often stronger than “maybe”): Varmaan syön puuroa aamulla.
luultavasti / todennäköisesti = probably/likely.
Verbal options: Taidan syödä… (I guess I will), Saatan syödä… (I might).

Is the partitive here because of the uncertainty from ehkä?

No. Ehkä doesn’t trigger partitive. The partitive puuroa is used because the amount is indefinite/partial (a mass noun). You can still use a total object with ehkä if you mean a specific, complete portion: Ehkä syön puuron aamulla (“Maybe I’ll finish that bowl of porridge in the morning”).

Could I use a plural like puuroja here?

Normally no. Puuro is a mass noun in this context, so you eat an indefinite amount: puuroa. The plural puuroja would mean “porridges” (several kinds or several portions), which is unusual unless you’re explicitly talking about multiple types/servings. If you want to specify one serving, use a measure word: Syön kulhollisen puuroa (“a bowlful of porridge”).