I have a similar class, and I feel your pain. However, there are a few things that have worked for me.
1. 31 Game. Maybe you know this one, as it's a common drinking game over here. One person starts, and they can say up to three numbers, for example, "1, 2" then the next person could say "3, 4, 5" then "6" then "7, 8" etc up until someone hits 31. They are the loser and get some kind of penalty. It's simple but does practice numbers and gets their mouths unglued.
2. Categories. This one is slightly more difficult, but still gets them talking. Basically just choose a category (food, stuff at school, animals, etc) and go around in a circle with each student saying a word that fits that category.
3. If you want to have some sort of conversation, give them a specific sentence structure to work with. "My favorite movie is___" or "Yesterday I did____" and try to go from there. Sometimes a more natural conversation will arise from that.
4. Card games. These can be hard to teach initially but once you get going it's really fun. Simple stuff like Go Fish and BS get them talking and help them relax.
5. Find out what they're interested in. If they're too shy to tell you, give them a questionnaire or something. It really helps to get them talking if you can bring up subjects relevant to their lives.
Anyways, good luck! Conversation classes can be pretty rough. Try to have fun!
