Learn Finnish: Mummo hoiti esikoista. - Granny took care of the firstborn.

The verb hoitaa (to take care of, to nurse) is a partitive verb. When you are taking care of a person, an animal, or a plant, it is considered an ongoing, continuous action rather than something with a clear endpoint, so the object must be in the partitive case.

What is the base form of esikoista, and how did it get that -sta ending?

The dictionary form is esikoinen (firstborn). For Finnish words ending in -nen, the partitive ending is always -sta or -stä, which completely replaces the -nen. That's why esikoinen becomes esikoista.

How does the past tense of hoitaa become hoiti?

To form the past tense (imperfect), we use the past tense marker -i-. For verbs ending in -aa or -ää (like hoitaa), the final vowel drops out before adding the -i-. So, the stem hoita- becomes hoiti-. Since this is the third-person singular ("Granny"), there is no extra personal ending added.

Could we ever use a total object (like esikoisen) with the verb hoitaa?

When hoitaa means "to nurse" or "to look after" a person, it always takes a partitive object. However, if hoitaa is used to mean "to handle" or "to complete" a specific task (like taking care of a bill, an errand, or a chore), it can take a total object to show the task was fully finished.