Where is the proper placement for quotations in this sentence?
Have you seen Harry Potter yet?
I would say the only thing that needs quoatatoin marks is "Harry Potter". But, the teacher put the whole sentence in quotation marks?

Ah, good question. Quotation marks can be used to show ships, planes, plays, etc. but they are also used to show words that have been spoken. In essence, you are both correct.

Jane said: "Have you seen 'Harry Potter' yet?"

Here's a lesson on double or single quotation marks.