well, I speak English as my first language, but took spanish for my credit. How our teacher managed us was strict- yes, but also fun. She spoke nothing but spanish too us, and forced us to listen to her by not writing the instructions on our papers that we had to do. She would give us the chance to pass notes- as long as they were in Spanish. And simple things like that. Just make the language a little more fun, and soon they will all want to speak it because it is more... entertaining than their first one.