Learn Finnish: Opettaja on koulussa. - The teacher is in the school.

In Finnish, you don't use a separate pre-word for "in". Instead, you attach the ending -ssa directly to the end of the noun. So, koulu (school) becomes koulussa. This is called the inessive case.

Why is the ending -ssa instead of -ssä on the word koulussa?

This is because of vowel harmony. The root word koulu contains the back vowels o and u, so it must take the back-vowel ending -ssa. If a word has front vowels (like ä or ö), you use -ssä instead.

Where is the word for "the" in Opettaja on koulussa?

Finnish doesn't have articles like "a" or "the". The word opettaja can mean "teacher", "a teacher", or "the teacher" depending on the context. The same goes for koulussa, which can mean "in a school" or "in the school".

What happens if I change the word order to Koulussa on opettaja?

It changes the focus! Opettaja on koulussa means "The teacher is in the school" (answering where the teacher is). Reversing it to Koulussa on opettaja means "There is a teacher in the school" (introducing new information about what is inside the building).