I need a reference letter

Kind of letter: Reference
Topic: reference letter for school application
Tone: Formal/Professional
Outline & Structure: I need to write a reference letter for a student of mine who applied to Westminster Under School. I'm his guitar teacher and I've been teaching him for about 2 years, one a week. He passed with merit - step one classical guitar and now his preparing for step 2. Here there're more informations about what I need to write in the letter:

They need to know whether he learns fast, whether he practices hard for his exam, that he tries to better himself and to pass the exam. Also whether he is young for his achievement? He is now 6.5year old. Finally that he managed Merit for his exam and that currently trying for the next level. They basically want to hear whether he has ambition and he has an ear for music. They have a big music part in that school and they also give scholarships for music. So they want to hear that there is potential there.
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