I'm hoping that nobody is monitoring my internet usage. I've just realised that my search for 'cooking children' on the BBC's website might be misinterpreted :-)
i have a 7 and 9 year old. they love to make toad in the hole, tuna pasta bake, pancakes, muffins, pastry. in fact pretty much anything as long as you supervise the safety part.
DIY pizza always goes down well. You provide the bases and a selection of toppings and the kids do the rest. They can make faces, patterns - all sorts.
We used to do sweet pizza too - chocolate, fruit, hundreds and thousands etc.