Learn Hardcore Icelandic: Stelpan er snjöll í stærðfræði líka.

Icelandic uses a suffixed definite article. The base noun is stelpa (girl). Add the article to get stelpan (the girl). Because the subject is specific, it’s definite and in the nominative case. Handy forms:

Indefinite nominative: stelpa
Definite nominative: stelpan
Other common singular forms: accusative stelpuna (def.), dative stelpunni (def.), genitive stelpunnar (def.); the indefinite oblique singular is stelpu.

Why is it snjöll and not snjall?

Adjectives agree with the noun in gender, number, and case. Stelpan is feminine nominative singular, so the predicative adjective takes the corresponding strong form: snjöll. Basic nominative forms:

Masculine: snjall
Feminine: snjöll
Neuter: snjallt

Does the adjective change if it comes before the noun?

Yes. Attributive adjectives before a definite noun take the weak ending:

snjöll stelpa = a clever girl (strong)
snjalla stelpan = the clever girl (weak + suffixed article) Predicatively (after a form of vera): Stelpan er snjöll (strong).

Which case does í take in í stærðfræði, and why?

Í is a two-way preposition:

Dative for location/state: í stærðfræði (in mathematics → area of skill)
Accusative for motion into: í skólann (into the school) Here it’s about a field, so dative. Stærðfræði doesn’t visibly change form here.

What does líka do, and why is it at the end?

Líka means also/too/as well. End placement scopes it over the immediately preceding phrase, giving “in mathematics as well.” Compare:

Stelpan er líka snjöll í stærðfræði. → The girl also is smart at math (perhaps in addition to someone else).
Stelpan er snjöll í stærðfræði líka. → She’s smart at math as well (perhaps in addition to another subject). Both are natural; the end position often reads like English “as well.”

Could I use einnig instead of líka?

Yes. Einnig also means “also,” but it’s more formal/written. Typical placement: Stelpan er einnig snjöll í stærðfræði. End-position einnig sounds bookish; líka is the everyday choice.

Why í and not á for “good at” a subject?

With areas of knowledge or skills, Icelandic normally uses í:

snjöll í stærðfræði, góður í ensku, klár í tölvum Á appears in other fixed phrases (e.g., spila á píanó = play the piano), but not for being good at a school subject.

What does er correspond to, and what are the present forms of vera?

Er is “is,” the 3rd person singular of vera (to be). Present tense:

ég er, þú ert, hann/hún/það er
við erum, þið eruð, þeir/þær/þau eru

What’s the difference between stelpa and stúlka?

Both mean “girl,” but stelpa is more colloquial and the default in everyday speech; stúlka is somewhat more formal or bookish.

How would the sentence change for a boy?

Switch the noun and adjective to masculine:

Strákurinn er snjall í stærðfræði líka. You could also use the more formal drengurinn for “the boy.”

Can I say góð í stærðfræði or klár í stærðfræði instead of snjöll?

Yes, with agreement:

Feminine: góð, klár, snjöll
Masculine: góður, klár, snjall Nuance: góður = good/competent; klár = clever/bright; snjall = skillful/brilliant (often a bit stronger or more formal than klár).

What’s the word-order rule here?

Icelandic main clauses are verb‑second (V2). The finite verb (er) comes in second position:

[Subject] Stelpan [Verb] er [Rest] snjöll í stærðfræði líka. If you front another element, the verb still stays second:
Í stærðfræði er stelpan snjöll líka.

Pronunciation tips for the tricky parts?

æ as in “eye.”
í like long “ee.”
ö (in snjöll) like German ö (rounded “e”).
ð like the th in this.
ll often sounds like “tl” (voiceless): snjöll ≈ “snyetl.”
Primary stress is on the first syllable of each word: STEL‑pan, SNJÖLL, STÆRÐ‑fræði, LÍ‑ka.

Why isn’t there an article before stærðfræði?

Fields of study are usually used without the article in a generic sense: í stærðfræði, í efnafræði, í sálfræði. Use the definite form when referring to a specific identifiable instance (e.g., a particular course): í stærðfræðinni (“in the math course/the mathematics in question”).