Aha..orbital..you actually teaching?
rule one..
don't turn your back.. as Ang sez.. act like as if you have got eyes behind your back.
Anmd that's the only rule..
try making it fun.. create a story..say they are the president  and need to create a landscape to capture some weird alien..etc.. and then you are the militairy officer in command.. who has the secret key to creating the perfect landscape for the aliens to land etc.. and way to go.. you've captured their attention..and teach.
never go into detail..will get them bored..they've only got a time span attention of a bee..
have way loads of fun though.. if you can capture their imagination. you've won them over..
let us know how it went!

And have fun!!

rayraz..tentacle monster button?? Lol..