How might you effectively encourage a classmate a participant in a class discussion

Try to notice what they already know, and if it's something they should know make a comment something similar to, "Hey, you know this right?", or "What do you think?"

Explanation:

However this won't always work. If it's a good student seeing that someone notices how smart they are, or how they view something, may make them want to answer more. However, every class has those kids who just don't care and don't want to talk, it's a good idea to get a good view of what kind of person it is you're trying to get involved.