How do we get kids to ask questions?

As a pre-service teacher, I often think about what I can do to get kids to ask questions. I noticed that at the beginning of the year, many kids in the Algebra class that I am observing did not ask questions. My cooperating teacher tells the kids all of the time that he wants them to ask questions and thanks them when they do. He always states that he cares about their learning and he makes himself available before school, during lunch, and after school. Over time, kids that never asked questions started to ask questions. However, there is still a large number of students that do not ask questions.

Some additional ideas that I have to get kids to ask questions are:

*Have students write their questions anonymously on index card.
*Give students points for writing questions on their homework when they don't understand.
*Make participation points apart of the class grade.

What are some methods that you would use to get kids to ask questions?