This is one of our class blogs where ads have been appearing recently.
The class teacher contacted me for advice and I suggested that the school could sign up to be an edublogs supporter and then there would be no more ads appearing on their site. I also pointed out that if any other teachers were keen to set up a class blog, then their blogs could be included in the school's 'ad free' package.
The school is happy to do that and the problem will be resolved soon.