Answer: here’s an example thats straightforward and simple.
Hi/dear (teachers name),
I’m emailing you to let you know that I will not be in class again on (put the date here) (state the reason why you will miss your class here ex: as I am still not feeling well) thank you for your consideration.
Sincerely, (your name)
example email:
Hi Mr. John
I'm contacting to let you know that I won't be in class again tomorrow because I'm still feeling unwell. Thank you for your consideration
Sincerely, (student’s name)