The most important thing to remember is it needs to be fun. It won't be easy to teach a group with a wide range in ages, and they may have various levels of abitlity. It seems to me it would be almost impossible for an experienced ESL teacher to find useful projects to work on together.

Maybe for the younger and weaker readers, you can find passages that are easier to read and leave the more difficult passages for the more advanced readers. They will hopefully build confidence in their reading, and that may well be the best thing you can do for them.

Most imortantly, everybody needs to have fun, including you!