I don't know where I caught this or from whom, but I really wish people would stay home when they're sick. That applies at school, also.
So many children go to school sick and spread whatever germs they have. I know that some don't have any symptoms until they get to school, but if they're sick in the morning, they should stay home.
Parents should, however, make sure they are truly sick before letting them miss school. Too often students stay home when they shouldn't and valuable learning time is missed.