I used to teach Art to school leavers, and I can definitely advise to keep things as simple as possible.
Try not to give them information overload, keep things more practical for them.
Explain, demonstrate and get them to do.
As they are only short sessions, I'd suggest the first, although might be a bit of an overload, just explain and show all the basic ingredients to make the meals and give printed recipe handouts.
Things like Base (inc. a small version that would be easy for them to make at home in the future), spices, spice mix, pre-cooked meat/veg, naans, g&g paste, tikka, kebabs etc.
Then you won't have to get them to make all those in the class, you make them yourself and bring them to the following sessions for them to actually start cooking.
Each session could then focus on them cooking one item, rice, naans, a few different style curries, some starters for example, and again printed handouts of the recipes they are cooking.
Hope that helps
Martin