R

R

This is your personal matter. Whether you want to discuss it with the fellow teachers or students depends on your circumstances, work envoirnment and relationship with the school staff/students. If you feel there is no harm to anyone and you want to share the news (people will take it positively), go ahead.

However, in most cases I have seen people don't share details and simply state that they were not feeling well and needed a break (this is not a lie). 

Dear Suelou,
Speaking from the point of view of a mother of a second grader  your students are too young to understand.
My second grade thal major child has no idea there is anything wrong with him inspite of transfusions. He's just happy to get an extra day off from school. 
Wishing you the best.
Zahra