My dd is in year 4 at a prep school - she has been there since she was 3 and has always had good attendance, but since September has had more time off than usual because she has been more ill than she usually is. Today I got (rather snotty) letter from the school to ask whether I am aware of the importance of school attendance - we have never had a letter like this before.It says she has missed 10% of school since Sept 12. Apparently her teacher also told her she has to 'try not to be ill' from now on 
I am a bit annoyed about this because of course I don't want her to miss school and neither does she as she loves school but she really has just been ill. Maybe I could understand if her attendance was poor year after year but it never has been. As far as I know her work is fine too and she is not behind.
Are these letters standard now?