What is it like to have a class teacher who likes to observe in secret?

Have you ever been secretly observed by a teacher in your student career? When the school bell is about to ring and you are still discussing with your classmates that girl is pretty, the teacher has quietly come behind you and is looking at you quietly. However, your classmates who are usually close to you are excited but silent at this time. Waiting to see your jokes. Sitting at the back door with a window is the most uncomfortable. Whether you want to check your phone or read a novel during class or self-study, you have to be on tenterhooks for fear that that familiar and majestic face will suddenly appear in the window. It’s really painful to have a head teacher who likes to observe in secret.