Taking notes

I have a computer supplied by the school board. It has been broken since last year so I sometimes can’t do my work. My mom has been trying to get me to take notes in history class so the other day I pulled out my phone and opened google keep. My mom showed me the app so I tried it. It was working pretty good and I was taking notes. My history teacher came around and pointed to my paper on the desk and said that the pen and paper were for note taking, not my phone and I had to put my phone away. He doesn’t understand.