Learn Finnish: Amerikka on iso manner. - America is a big continent.

In everyday speech, Finns sometimes say Amerikka when talking about the USA. However, because this sentence calls it a manner (continent), it is talking about the geographical landmass. The official Finnish word for the United States is Yhdysvallat.

How would I say "on a big continent"? Does the word manner change?

Yes, manner has a tricky stem that is good to learn at this level! When you add endings to it, the word changes to the stem manteree-. To say "on a big continent", you also have to match the ending on the adjective, giving you isolla mantereella.

Why are iso and manner in their basic forms instead of the partitive case?

This is a classic "A is B" sentence. Because a continent is a countable thing (you can have one continent or two continents), the describing words stay in the basic nominative form. If you were describing an uncountable mass word instead, like water, you would use the partitive (for example, vesi on kylmää meaning "the water is cold").

Since this lesson is about the perfect tense, is this sentence in the perfect tense?

No, this sentence is actually in the simple present tense! It only has one verb: on (is). However, it is a great reminder because on is the exact helping verb you need to build the "he/she/it" form of the perfect tense. To make this a perfect tense sentence (like "America has been a big continent"), you would keep on and add a past participle verb, like Amerikka on ollut iso manner.