Thanks 
Funnily enough I mentioned to them about there being a number of different things that alter Dof but did not want to go further explaining in case I stood on the teachers toes .... though it seems there is no input other than take some photos with shallow Dof ... not how 
I think as it is their first 'serious' camera and I am unsure what they want to do with it may well be best to just see what happens and go from there.
Depending on what they do and say, that will dictate another zoom or a cheap prime.
