At least once a semester, you should do an activity that allows students to learn each other's names and have a laugh together. When students feel they know each other personally, they are more likely to speak during classroom discussions. It can be as simple as going around the room and having each student say his name and one quirky, personal fact. Another activity is to have each student say his name, as well as every name that came before him in the sequence. Students will laugh together as the last student struggles to remember each name in the class.
Especially for college and university courses, a drop in classroom participation can be due to students not coming to class prepared with the readings done. Overcome this problem by requiring that each student come to class with a thoughtful question prepared about the week's material. Stipulate that the question must be written out and submitted at the end of class, and must have a preamble of a few sentences. This ensures that students don't jot down something quickly before class. If you are stuck for conversation during the period, ask any student to read his question aloud.
Students sometimes feel too intimidated to speak in front of a large group of people. Conquer this shyness by dividing the class into small discussion groups for any topic. Give the groups one or two major questions to think about and have them discuss each one for five to ten minutes, then reconvene as a collective. Ask each group to present their findings briefly to the rest of the class.
Making one student responsible for material ensures that at least one student will participate fully. At the beginning of the semester, circulate a signup sheet for presentations on individual days. Students whose turn it is to present must write a five minute paper or oral presentation to be delivered to the rest of the class. Require the student to include two or three discussion questions at the end of their presentation to engage the other students.