Learn Finnish: Hän on amerikkalainen opiskelija.

While amerikkalainen is a nationality formed with the suffix -lainen rather than a compound property adjective, it behaves exactly the same grammatically. Just like sinisilmäinen becomes sinisilmäisen, amerikkalainen changes its -nen to -se- to form its stem, making the genitive amerikkalaisen.

Why isn't amerikkalainen capitalized like 'American' is in English?

In Finnish, adjectives and nouns derived from proper names are always written with a lowercase letter. This applies to nationalities, languages, and residents of a city. You only capitalize the name of the place itself, such as Amerikka.

As a quick refresher, why use opiskelija instead of oppilas here?

Opiskelija specifically refers to a student in higher education, such as a university, college, or adult education program. Oppilas refers to a pupil in primary or secondary school. The use of opiskelija tells us he is likely an adult at a university.

How would this sentence typically change in everyday spoken Finnish?