Learn Hardcore Icelandic: Sumir nemendur lesa, aðrir skrifa.

Sumir means some (of a known or defined group) and strongly suggests a contrast with the rest of the group – which is why it so often appears with aðrir (others).

Sumir nemendur lesa, aðrir skrifa.
Some (of the) students read, others write.

Compare:

nokkrir = some, several (a few, without necessarily contrasting with others)
einhverjir = some (unspecified, “some or other”, often more indefinite or vague)

So:

Sumir nemendur lesa, aðrir skrifa.
Highlights: one part of the same group does X, another part does Y.

If you just wanted to say “Several students are reading” with no built‑in contrast, you’d more likely use nokkrir nemendur lesa.

Why is it sumir nemendur and not sumar nemendur or something like sum nemendur?

In Icelandic, determiners like sumir must agree with the noun in:

gender
number
case

Nemandi = student (masculine noun)
Nominative plural = nemendur

So the matching nominative masculine plural of sumur (“some”) is:

Masculine nom. pl.: sumir
Feminine nom. pl.: sumar
Neuter nom. pl.: sum

Therefore:

sumir nemendur – correct (masc. pl. + masc. pl.)
sumar nemendur – wrong, because sumar is feminine plural
sum nemendur – wrong, because sum is neuter plural

Example with a feminine noun:

bók (book, feminine) → bækur (nom. pl.)
→ sumar bækur = some books

With a neuter noun:

barn (child, neuter) → börn (nom. pl.)
→ sum börn = some children

What case are sumir nemendur and aðrir in, and why?

Both sumir nemendur and aðrir are in the nominative plural, because they are the subjects of their respective clauses:

Sumir nemendur (subject) – lesa (verb)
aðrir (implied nemendur, subject) – skrifa (verb)

In Icelandic, the subject of a normal (non‑quirky) verb is in the nominative case, just like in English we say they (not them) as the subject.

You can see the nominative plural forms:

nemendur – nominative plural of nemandi (student)
sumir – nominative plural masculine of sumur
aðrir – nominative plural masculine of annar (other)

Why is there a comma before aðrir? Would English use a comma there too?

Icelandic allows a comma between two full main clauses more freely than standard written English does.

Sumir nemendur lesa, aðrir skrifa.
literally has two independent clauses:

Sumir nemendur lesa.
Aðrir skrifa.

In English, you would normally write this as:

Some students read; others write. (semicolon)
or
Some students read. Others write. (two sentences)

Using a simple comma between two full clauses in English (Some students read, others write) is considered a comma splice and is usually marked as incorrect in formal writing, but it is normal in Icelandic.

Why don’t we repeat nemendur in the second part? Could we say aðrir nemendur skrifa?

Icelandic often omits a repeated noun when it’s clear from context. Aðrir here means other (ones), and the noun nemendur is understood:

Sumir nemendur lesa, aðrir (nemendur) skrifa.

You can say:

Sumir nemendur lesa, aðrir nemendur skrifa.

That is grammatical, but it sounds heavier and more repetitive. The shorter version with just aðrir is more natural in this pattern sumir … aðrir ….

What exactly is aðrir grammatically, and what are its other forms?

Aðrir is the nominative masculine plural of the pronoun annar meaning other / another.

Annað is irregular. Key forms:

Singular:
- masc.: annar
- fem.: önnur
- neut.: annað
Plural:
- masc.: aðrir
- fem.: aðrar
- neut.: önnur

In our sentence, the implied noun nemendur is masculine plural, so we use:

aðrir (nemendur) – other students (masc. nom. pl.)

Example with a feminine plural noun:

Sumar konur vinna, aðrar hvílast.
Some women work, others rest.

Why is it lesa and skrifa here, and not les or skrifar?

Both lesa and skrifa are in the 3rd person plural present tense. They agree with plural subjects:

Sumir nemendur (they) → lesa
aðrir (nemendur) (they) → skrifa

Conjugation of að lesa (to read):

ég les – I read
þú lest – you (sg.) read
hann/hún/það les – he/she/it reads
við lesum – we read
þið lesið – you (pl.) read
þeir/þær/þau lesa – they read

Conjugation of að skrifa (to write):

ég skrifa – I write
þú skrifar – you (sg.) write
hann/hún/það skrifar – he/she/it writes
við skrifum – we write
þið skrifið – you (pl.) write
þeir/þær/þau skrifa – they write

So with a plural “they” subject, you use lesa and skrifa.

Is the word order fixed, or could I say something like Sumir nemendur lesa, skrifa aðrir?

You cannot say … skrifa aðrir in a neutral main clause; that would violate the verb‑second (V2) rule in Icelandic.

In main clauses, the finite verb must appear in second position:

Sumir nemendur (1st slot: subject phrase)
lesa (2nd slot: verb)

In the second clause:

aðrir (1st slot: subject)
skrifa (2nd slot: verb)

So:

Sumir nemendur lesa, aðrir skrifa. – correct
Sumir nemendur lesa, skrifa aðrir. – wrong in normal word order

You can move things around in questions or some special emphatic constructions, but for a normal statement like this, keep subject–verb order as shown.

How would the pattern change if the noun were feminine or neuter?

The structure sumir … aðrir … stays the same, but sumir / aðrir change to match the gender of the noun.

Feminine noun example (bók – book):

Nominative pl. = bækur
Some books are interesting, others are boring:
- Sumar bækur eru áhugaverðar, aðrar eru leiðinlegar.

Here:

sumar – fem. nom. pl. of sumur
aðrar – fem. nom. pl. of annar

Neuter noun example (barn – child):

Nominative pl. = börn
Some children sing, others dance:
- Sum börn syngja, önnur dansa.

Here:

sum – neut. nom. pl. of sumur
önnur – neut. nom. pl. of annar

So the pattern is:

Masculine: sumir … aðrir …
Feminine: sumar … aðrar …
Neuter: sum … önnur …

How do you pronounce sumir, nemendur, lesa, and aðrir, and where is the stress?

Approximate pronunciation (IPA + rough English hints):

sumir – /ˈsʏːmɪr/
- Stress on the first syllable: SU‑mir
- u is like the short u in German Müller, not like English oo.
nemendur – /ˈnɛːmɛntʏr/
- Stress on the first syllable: NE‑men‑dur
- The ur at the end is quite short and reduced.
lesa – /ˈlɛːsa/
- Stress on LE‑: LE‑sa
- e like in English bed, but a bit longer.
aðrir – /ˈaðrɪr/
- Stress on Að‑: Að‑rir
- ð is the voiced th sound in this.
- Final -rir is quick.

In Icelandic, primary stress is almost always on the first syllable of the word.

Could we also say Sumir nemendur lesa og aðrir skrifa? Is there any difference?

Yes, you can say:

Sumir nemendur lesa og aðrir skrifa.

The meaning is basically the same: Some students read and others write.

Very small nuance:

With a comma: Sumir nemendur lesa, aðrir skrifa.
→ Feels slightly more like two separate statements placed side by side.
With og: Sumir nemendur lesa og aðrir skrifa.
→ Feels more like a single combined sentence with a straightforward and connection.

Both are natural and correct.

Can I put another determiner like þeir with sumir nemendur, e.g. Þeir sumir nemendur lesa…?

No. You don’t stack þeir with sumir in front of nemendur like that.

Sumir nemendur already means some (of the) students.
Adding þeir (they/those) before it (þeir sumir nemendur) is ungrammatical.

If you want to say those students, some read and others write, you could say for example:

Af þessum nemendum lesa sumir, aðrir skrifa.
Among these students, some read, others write.

How would you negate this idea: “Some students don’t read; others do (read)” in Icelandic?

One natural way to say this is:

Sumir nemendur lesa ekki, aðrir gera það.

Literally:

Sumir nemendur lesa ekki – Some students do not read
aðrir gera það – others do (do that)

Key point: ekki (not) goes after the verb lesa:

lesa ekki – do not read

You could also be more explicit:

Sumir nemendur lesa ekki, en aðrir lesa.
Some students do not read, but others read.