Are you able to demonstrate? If not, that’s fine but find someone in your area that can demonstrate. There may be teachers at your campus that played flute in high school that could help. Another option is to show videos on YouTube that they can watch and more importantly hear what they are to sound like. Spend lots of time with the headjoint but remember the trick is balancing the whole flute together. Man I wish I could be more helpful. Where are you located?