That pupil tsk tsked the teacher.
We call students "pupil" up through high school, but we don't call university students "pupils."
My hobby is reading books about the forbidden love between students and their teachers.
One who is junior in life is a student or pupil. It's kind of like how a 先生 is someone who came previous to you in life. Cool how that works, right? Okay 生徒, get back to work!
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.