Questions & Answers about Opettajalla on hyvä idea.
Why doesn't this sentence use a verb for 'to have'?
Finnish does not have a single verb that means 'to have'. Instead, it uses a structure that literally translates to 'at someone is something'. Here, opettajalla means 'at the teacher', followed by on ('is') and the thing they have (hyvä idea).
Why is the ending -lla attached to opettaja?
Why are hyvä and idea in their basic forms? Do objects not usually get an ending?
That is a great observation! In a standard action sentence, the object usually gets an ending. But in the Finnish 'have' structure, the thing being owned (hyvä idea) is grammatically the subject of the sentence ('A good idea is at the teacher'). Because it is the subject, it stays in the basic dictionary form.
How would I say 'The teacher does not have a good idea'?
You would change on to ei ole ('is not'). Remember that when you make a 'have' sentence negative, the thing being owned must change to the partitive case. The sentence would become: Opettajalla ei ole hyvää ideaa.