if you don't pay attention to the teacher's speaking,you will porbably miss some important part of the points.If you play or sleep during the lesson,you will gradually lose interest in English,as a result,you will fail yourself.
To be a good learner,you should always pay attention to your teachers and take notes from time to time,actively take part in the questions raised by the teachers and think of questions on your own.If you meet problems,bravely stand up and face the teachers.