How to write an email back to teacher

I was at a marching band practice the other night and I just received an email stating that I wasn’t there when I was so I was wondering how I can write an email back to my band teacher stating that I was there at rehearsal

Hello Mr./Mrs. Name,

I believe I have received this email in error. It says that I was not at practice on Tuesday the fifth, but I have not missed a practice yet this year. What can I do to set the record straight? If it helps, I distinctly remember being there when (memorable detail from practice that night, if you can come up with one).

Thank you so much,
Your Name

The blanks would obviously be filled in (and don’t keep the “yet this year” if you have missed practice, haha).

As for the memorable detail–did you talk to your teacher at all that night? Did you answer a question, lead your section, play a solo, anything that your teacher might remember you doing?

I don’t really understand your question. Just hit reply and politely tell him/her that you were at practice.