Sample Method

I would like to survey the number of people has been going to after school in the whole school for the past week. I will sample 5 people from each 7, grade class.

Random Sample; I would randomly sample the first 5 compassion students who comes to after schoool.
Convenience Sample; I would sample the people who is in Ms.Sa after school.
Biased Sample; I will sample all the people who would come out of school after After school is over.