[MMM]

Those kinds of pronunciation exercises are going to be too hard and frustrating the first day. Practice "get to know you" exercises.

Introduce your self in about 5 sentences. Then ask the group to answer questions about you. "Where was I born? How old am I?"

Then have each of them write their own intro and read it to the group. They you can ask the group questions about each individual.

This way you can gauge their English, and it's not that much work for you.