I found a wallet on the street, so I handed it in to the police.
If you hand in your notice or resignation, you tell your employer, in speech or in writing, that you no longer wish to work for them. I handed my notice in on Saturday All eighty opposition members of parliament have handed in their resignation
submit school work, submit homework (e.g.: "I'd better get started on my book-report, I have to hand it in first thing tomorrow morning")
If you hand in something such as homework or something that you have found, you give it to a teacher, police officer, or other person in authority. I'm supposed to have handed in a first draft of my dissertation My advice to anyone who finds anything on a bus is to hand it in to the police