The ability range you have in the class already makes it problematic, but I suspect the class is extra difficult because of the kids' wide range of age. I would suggest watching some videos - things like Teletubbies or Sesame Street which parents often watch with their kids, but you run the risk that what's right for the 3 yr olds will bore the 8 yr olds and vice versa.
But I wonder what the parents were expecting? How was the course sold to them? They must surely realise that the content and activities must be geared to the kids? You don't say where you are or if you speak their language, but it might be useful to have a meeting, with an interpreter if necessary, to discuss their objectives in coming and to make sure that their expectations are realistic and that they recognise that their participation is essential.
I liked the idea of doing crafts and practical activities, and at the meeting you could also find out if they have any special skills that they could teach to the class. Origami springs to mind, but simple cookery (if you've got the facilities) or whatever. You could start by teaching a bit of vocab, and then the parent could then teach the kids and others how to make a paper frog, or biscuits etc. Simple scientific experiments are another possibility.
Have a look at
http://www.nationalgeographic.com/kids/activities/
for ideas.
Edit - Sorry. you did say where you were from.