How many of your students participate in class?

A teacher asked me the other day about how I get my math students to participate in class.  She stated that she always had the same students answering questions.  I told her that my students have no choice but to participate.  I explained to her that it starts the first day of school.  I tell all of my students that they will participate on a daily basis.  I explain that I will call on students and I will call students from my class list.  This way everyone participates.  When a student’s name is called, the student already knows that he/she will need to answer the question or go to the smart board or chalkboard and put up an answer.  In the beginning, the shy students always have to be called by me.  However, as time passes they begin to volunteer.  All of my students know that it is okay to participate on a daily basis even if he/she makes a mistake.