If silent people are meeting dropouts - reading a newspaper, yawning, rolling their eyes, almost reclining in their chairs - you might consider their purpose in being at the meeting. They may be indifferent to the topic, think the meeting is a waste of time, be bored, or feel that they will have nothing to contribute. One way to get them participating is to stand close to them. Establish eye contact, call them by name and ask them a question. If they don't answer quickly, say, "I'll give you a moment to think" and call on someone else. One thing you should definitely do is ask them to put away their reading material.
On a break, ask them why they are not talking. Just showing them your attention may help them tell you the reason for their behavior, which could be pressing issues at work or preoccupation with other matters. Other participants will notice how you handle this.
If silent persons are simply shy, they may look uninvolved, but they are really tracking with you and the meeting content. You can establish eye contact, smile, and ask them an open question—one that needs more than a yes-or-no answer. When they've finished, sincerely thank them to encourage further participation. If you split the class into subgroups, ask silent persons to summarize the discussion. You can also ask a question and have each person in your meeting group respond by sharing their opinions. Interact with them during a break to discover more about their perceptions on the meeting topic; if you can gain their trust, they may contribute more. Silents often process their thoughts deeply, so their responses may not be frequent, but they are nearly always worthwhile.