Learn Icelandic: Ætlar þú að sleppa kóræfingunni í dag? - Are you skipping the choir practice today?

The verb sleppa governs the dative case. Whenever it means to skip an event (like this practice) or to let go of something, the object being skipped or released must take the dative form.

How does the ending of kóræfingunni work to show the definite dative?

The base word is kóræfing, a feminine compound noun ending in æfing (practice). In the dative case, æfing becomes æfingu. To say the choir practice, we add the feminine dative definite article -nni to the end, resulting in kóræfingunni.

Why does the Icelandic sentence use Ætlar þú að instead of a direct translation of Are you skipping?

Icelandic uses the verb ætla (to intend or plan) plus að to talk about future actions. While English often uses the present continuous to express a set plan for later today, Icelandic naturally expresses this intention with ætlar þú að sleppa.

Does sleppa always take a dative object?

It takes a dative object when it is used transitively to mean to skip or to let go of. However, sleppa can also be used as an intransitive verb (meaning it takes no object at all), in which case it means to escape or to get away.