You will likely need to request a letter of recommendation or a reference from your horn teacher at some point.
Follow these steps to deal with this in an efficient and professional way.
Ask your teacher if he/she would be willing to write a recommendation. If you anticipate needing many recommendations over the course of several months, be sure to mention this up front. Then you won’t have to ask each time.
Gather the information your teacher needs. Sometimes there is a hard copy paper reference form, sometimes the form must be completed online. Sometimes what’s needed is a free-form letter.
If the recommendation is a hard copy paper form, provide your teacher with an addressed envelope. If it is to be sent directly to the school/organization, put a stamp on the envelope.
If the reference is free-form, also prepare a stamped, addressed envelope. Try to find the name of a specific person the letter can be addressed to if this is not clear from the address. This makes a better impression than if the letter salutation is: “To Whom it May Concern”
Be sure to let your teacher know the deadline date for the recommendation to be received.
Allow at least two weeks for your teacher to complete the recommendation. Remember that it is likely he/she will have quite a few recommendations to complete, all within the same time frame. (For example, if several students in your studio are applying for graduate school, your teacher will be completing recommendations for all those students, and the recommendations will all be due right around the same time.)
One week before the due date, either by email or in person, politely ask your teacher if he/she has had a chance to complete the recommendation.
Thank your teacher for the recommendation!