The first time I am the teacher

The head teacher came into my class and told us all that our teacher was sick, today "Therefore, I am going to choose a student to teach the class today." he said. To my surprise, he chose me so, I went up to the white board and I was telling the student to do the practiced, activity, and doing some exercise. Many of the students they were do this exercise but some students weren't do the exercise, and I thought they weren't listen to me because they maybe thought that I am not their teacher, and the next time I teach them to did the grammar, homework, if they weren't understood I was explained to them. This is the first time I was the teacher so, I was feeling surprised, happy when I teach them.