Explanation
We are given the following:
A teacher asks the first five students that walk into her room if they prefer getting to class early or late.
We are expected to determine if the situation is biased or unbiased.
We know that in a biased sample, one or more parts of the population are favored over others, whereas in an unbiased sample, each member of the population has an equal chance of being selected.
Therefore, the situation is biased because the teacher gives preference to the early arrivers in her room.