Thank you for contacting iTunes Store Customer Support. I'm Bernardita, I'll be the one assisting you today. I understand that you want to know if you can install iTunes in a network computer in your school so your music teacher will be able to present his iTunes purchases in your school via projector. I can certainly appreciate how eager you must be for answers, and I will provide as much information for you as I can.
Yes you may, you can install iTunes for as many computers as you can in your school. However, please inform your music teacher that in order for him to play his purchases on your school's computers, he needs to authorize those computers using his iTunes account and the maximum authorization that are allowable is up to five computers only.
I hope this email helped clarify it for you. If you have further questions, please reply to this email and I'll be happy to assist you. Have an awesome day!
iTunes Store Customer Support