I'm gonna back up here a bit and suggest you teach him how to tune the guitar by ear so that it is in tune with it self.If he's not in tune, he's wasting his and your time.
...after that...you may want to teach him an alternate tuning,preferably an open chord tuning,to get some right hand rhythm,strumming foundation down.
...and of course like some other people mentioned.....explain to him(first thing) what the bridge,the nut,the saddle,the frets,ect,ect,are .... just getting him aquainted with the instrument,all it's parts and what their functions are.JMO.