Any tricks for in class?

Any tricks for in class? Hello, I'm 15 and I have a speech block. I don't have i that bad but still enough that it bothers me. Its always when I have to answer a question then I can't get it out so I just pretend like I don't know the answer. A moment later when no one is listening I try to say it again and it goes pretty smoothly. Does anyone know tricks or anything that makes me get the word out faster?