Response to Andrew, "Being Called Upon"

Andrew discussed the multiple reasons why a student may not be able to answer a teacher's question when called upon in class, and concludes that even if the student is allowed to say "pass", the student may still be embarrassed by clearly not knowing the answer. I think that another reason students should not be called on in class is the fact that the classroom does not exist in a vacuum. Each individual student comes from a very different home and, especially in compulsory education, teachers should act under the assumption that students are coming from a bad environment or situation to be on the safe side. For example, in my elementary school, we were required to get our agendas signed by our parents every night, to ensure that they knew what our homework was. However, this put certain students at a disadvantage. If a student had parents that worked late hours, or didn't have a large presence in their child's life, the student may not be able to get their parents' signature. Similarly, some students may have social anxiety or a fear of public speaking, which would make being called on a traumatic experience. Teachers must be mindful of the fact that all students come from very different backgrounds. It would be nice if we could assume every student were perfectly adjusted and went home to a loving, functional family every afternoon, but, as Allison said, you must deal with the students you have, not the students you wish you had.

Question: How can a teacher be respectful of the various backgrounds students come from?