Schools know that they are primarily a babysitting service: it's easy to understand from the nature of the fuss that parents make when school is closed on a work day.
:) Since UK schools are considering experimenting with shorter/different summer holidays for the educational benefit, there was a parent on talk radio just this morning saying this was unfair because he may need to organise more babysitting.
Luckily, most parents are looking for good education.
