13th Picture on phone

When I first got to the class, I was so exciting about the new environment and new material. After listening the new lesson, the teacher began to write down today's assignment. At this time, some interesting thing happened. I saw some student began to take out their phone. "What that for?" I asked. "Oh, to remember the homework!" they answered me. What? You don't need to write it down on the notebook but just take the phone of it? That's interesting!! After that, I took the first assignment when I got to this school.