Learn Icelandic: Kennarinn þarf að skoða kortin. - The teacher needs to examine the cards.

The base word is kort (a neuter noun meaning "card"). In the plural, the bare form stays exactly the same: kort ("cards"). To say "the cards", we add the definite ending. For neuter nouns in the plural, this ending is -in, making it kortin.

Why is kortin in the accusative case here?

It is the direct object of the verb skoða ("to examine"). In Icelandic, verbs dictate the case of the objects that follow them. Skoða is a very common verb that takes its object in the accusative case. (Note that for neuter words like kort, the accusative form looks identical to the nominative form).

Does kennarinn mean "the teacher"? Where is the word for "the"?

Yes! In Icelandic, "the" is usually attached to the end of the noun rather than standing alone. The base noun is kennari (a masculine noun for "teacher"). Because it is the subject doing the action, it is in the nominative case. We add the masculine definite ending -nn to get kennarinn.

Why do we need the word að before skoða?

Að is the infinitive marker, functioning exactly like the word "to" in the English phrase "to examine". When you connect a conjugated verb like þarf (needs) with an action in its dictionary form, you use að + the infinitive verb.