I think it is a good idea, everyone in my district had to take cooking classes (as well as electric, wood, plastics, printing, sewing, metal, leather and home ec) for three years.
I just don't think it will have any effects on obseity. It will still be easier to throw a ready meal in the oven.
If knowing how to cook made you within your weight range then no one over the age when the classes stopped would be fat, aside from those who learned how to cook at home.