Q: Can I say, "I amend the 5th" when I get questioned by the police in school?

A: Yes, but some people might make fun of you.

A: I'll assume you mean "plead the fifth". That right is so gravely misunderstood by the general public as to almost be comical.

If you are questioned by police about something they believe you did, then yes, you have an absolute right not to incriminate yourself.

"Pleading the fifth" comes into play, usually, when you are questioned about your involvement in someone else's case and when your answers may subject you to criminal penalties.

Take, as an example, a drug transaction. A dealer gets caught, and police suspect you purchased drugs from that dealer. They might want or need you to testify to that fact, but if you did so, you would necessarily be admitting to possessing drugs, which is a crime itself.

Now, to get around that, and which defeats your right to "plead the fifth", the prosecutor may offer you what's called immunity from prosecution. That is an agreement, on the record, that you will not be prosecuted for what you say you did.

So going back to my example: prosecutor could tell you "if you tell us you purchased drugs, you won't be in trouble for possession". If that is offered, you can then be compelled to testify, and if you refuse to do so, you could be held in contempt. Now, that protection only extends to the crimes arising from the transaction you're testify about. If you then said "yeah, I purchased those drugs, but then went down the street and killed somebody", they could use your testimony to prosecute you for murder, but not drug possession.