Ask a question and an engaged and enthusiastic student answers - great answer. Next question same student. I like the suggestions in the study of giving students color cards and asking for answers from certain color sections. However, I usually ask students to raise their hands when the question requires a specific answer, that way I can say, "Angela you give such well thought out answers I would like to hear from some of the other students. If the discussion requires open ended answers, I might have students get into groups of three and discuss the answer for 3 min. before I ask the groups to contribute their answers in an open forum.