Oh, the partitive. Voi sinua, partitiivi. Miksi olet niin vaikea? Many Finnish learners face challenges when they're studying the use of partitive. While I think that learners should accept the fact that it will take time to fully master the differences between the accusative and the partitive, I'm determined to help you by giving you some common examples of these two cases. Just bear in mind that all of these sentences are affirmative (i.e. positive). If we were dealing with negative sentences, questions or commands, different rules would apply.
- The verb has several meanings. Here, I've used the accusative when I'm talking about picking someone up from school. However, when the meaning is to apply, I'm using the partitive.
- to wake someone up
- You could think of the act of waking someone up as a very straightforward action that has an end result. The speaker is assuming that they will succeed in waking up their dad, therefore, they're using the accusative case.
- to help someone
- You can almost always count on the partitive being the correct choice of case with auttaa. There are instances where you might see the accusative here but then you'd have to add other, more advanced elements to it, too. When it's this simple a sentence (X helps Y), then partitive it is.
- Essee is in the accusative because the speaker is saying he/she is going to write and FINISH the essay in one day.
- As soon as you switch to the partitive, we're not sure whether the essay is going to be finished or not. The main message here is that the speaker is writing/going to write at least some of the essay. There is no commenting on how much writing will be done.
- kutsua + accusative = to invite someone (somewhere --> often in the illative/allative...)
- kutsua + partitive = to call someone (something; nickname etc. --> often in the translative case, -ksi)
- the classic example: with the accusative, the speaker has eaten the whole cake, whereas the partitive expresses that he/she ate cake, but we don't know how much of it, just that they ate some.
- uuden auton - the accusative tells us that this singular object was bought in its entirety, a very straighforward and clean-cut purchase of a countable item.
- uutta saippuaa - the partitive used to express that some type of new substance was bought, a new type of soap. You could use uuden saippuan, here, and the meaning would be roughly the same, but you would probably be thinking about the countable item, the packed product. To give you another, possibly better example: 1. Minä ostan kaupasta kahvia = I buy coffee from the supermarket (to use at home most probably). 2. Minä ostan kahvin. = I'm gonna get a coffee (like a take-away or a cuppa ("a portion") from a cafe)
- This verb means to receive/to get in this context.
- the accusative is used because she got the whole job and nothing but. The act is seen to have an end result. Just like in the car purchase example.
- But when it's about receiving or getting something "indefinite" like some feedback, then you use the partitive. You could also say Hän sai palautteen which could mean that He/she got the feedback (that had been talked about and that he/she was probably expecting from someone).
While there are lots of rules, you'll always find exceptions and more advances uses, idiomatic expressions, alternative ways to say things... I don't think that anything can beat getting as much listening and reading done as you can because you need to be exposed to a lot of input in your target language. Knowing some rules will help to draw conclusions but please don't get discouraged when you come across exceptions to rules!