Instructions
Click on the avatar of one of the adults on the lot. Click on the telephone and invite the headmaster over for dinner.
Instruct someone in the house, preferably the person with the highest cooking skill, the serve dinner 15 minutes (Sim time) before the headmaster is to arrive.
Greet the headmaster. Offer to take him on a tour of the house. Walk to each room of the house. The headmaster will follow and say his opinion.
Click on the headmaster and tell him it's time to eat once you see that the food is done. Eat dinner. Click on the teen's avatar, and then click on a plate of food to tell her to eat.
Talk to the headmaster after dinner. Keep the conversation going until the timer runs out and the evening ends. He will tell you if the teen can attend private school or not.