If students want to concentrate, they need to put letters on the board and have someone come out and throw chalk at the letters or underline them. Just putting up a PPT and reading will reduce concentration... It's not like the star lecturers in the neighborhood just put letters on the board and bang the innocent board with their fists or make strange expressions and gestures to make a show. Even if you just read the letters quietly and leave, it would be better if a human came out and became one with the letters. If you're paying a lot of money to buy a PPT, if only the PPT appears on the screen and a voice echoes from somewhere, you won't know if it's being read by an AI or a human. If you're embarrassed to show your face in class, you can just wear a plastic bag with holes for your eyes, nose, and mouth.