One thing you can try is to have them do some role-playing conversation between themselves. Type up a conversation script that focuses/includes the vocabulary and/or grammar you are targeting in your lesson. Then hand that out to all of them and have them practice with each other. Then you circulate around the room and monitor/encourage/correct their conversation.
Better yet: Make 3 or 4 different conversation scripts. Hand them out, have them practice them out loud, and then SWITCH scripts and practice the next one.
Then, you can see if any of the groups would be willing to practice their script OUT LOUD in front of the whole class.
Just some ideas. I used to teach high school ESL.
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