What is an exit ticket?
An exit ticket is the last retrieval of the lesson: every pupil shows what they learned today, briefly and without the book. It works twice. The pupil pulls the material from memory once more, and that retrieval strengthens memory more than rereading. And you know at the door what to do again tomorrow.
So a lesson closure is not the teacher's summary. That feels useful, but then the class does nothing; the retrieving has to be done by the pupils.
Which structure for the last five minutes?
This page lists the structures of which one round fits in five minutes. Taking Turns is the simplest: everyone names one thing that stuck, and whoever has nothing passes. Knowledge Quiz, Shuffle & Pick and Movement Quiz work as an exit ticket with questions: every pupil answers a few, and you hear at once where it still chafes.
For the closing, prefer a structure the class already knows. A familiar one starts in twenty seconds; a new one costs two minutes of explanation, and you do not have them at the end of the lesson.
What to watch for
Plan the closing in, or it disappears: the explanation runs over, the bell goes, and the class leaves without retrieving. So put it in as a fixed block at the end of your lesson, with the time on the board.
Ask about today's lesson goal, not about everything. One or two questions that hit exactly that goal tell you more than ten about the whole chapter. And start the next lesson with what the exit ticket showed you.