Learn Finnish: Lapset saavat aina omenoita tontuilta. - The children always get apples from the elves.

Tontuilta is in the ablative plural, meaning "from the elves". First, consonant gradation changes the strong double -tt- into a weak single -t-. Then, we add the plural marker -i- followed by the ablative ending -lta, giving us tontuilta.

Why do we use the ablative case (-lta) for "from the elves" instead of the elative case (-sta)?

In Finnish, when you receive something from a person, animal, or character (like an elf), you use the ablative case, which indicates movement from someone. The elative case (-sta or -stä) is mainly used when moving out from inside a physical place or container.

Why is the word for apples (omenoita) in the partitive plural here?

The children are receiving "apples", but not a specific, defined number of them. When you talk about an undefined amount of a countable thing in the plural, you use the partitive plural. For the word omena, adding the plural -i- changes the final -a to an -o-, and then we add the partitive ending -ta.

I remember the word for child is lapsi. How does it become lapset here?