But Lin Yu didn't realize she was being watched by a camera.
It was the female teacher who had just bumped into Rui Ling. She had originally left to go home but realized halfway through that she had forgotten something. When she returned, she found Lin Yu tutoring a student.
This provoked her jealousy, and she instantly took out her phone to take many surreptitious photos.
Both Lin Yu and Rui Ling had their backs towards the door, oblivious to the camera pointed at them.
The female teacher, who had taken nearly twenty pictures, looked at her ill-gotten gains on her phone with satisfaction and left, forgetting all about the object she had left in her office.
Once home, she sifted through the pictures and sent them anonymously to the school director.
The photos were presented as evidence that Lin Yu was privately tutoring students and fundraising illicitly, in severe violation of school rules.
