While I see your point of misusing children to evoke an emotional response, I think this is an exception: 1) School is a mandatory part of life for every child

While I see your point of misusing children to evoke an emotional response, I think this is an exception: 1) School is a mandatory part of life for every child, therefore increased scrutiny and high standards are warranted. As an adult, you are free to go if you ever disagreed with your employer on ethical grounds. But if children were forced to participate in a dubious (in terms of privacy) online service, they really have no choice other than to accept it (going to another school in the same area is hardly a realistic option). 2) In general, it is understood that children might not be able to grasp all consequences of their decisions. Even if children had a choice whether to accept their school's mandatory online services, I don't think they can really give consent considering they might not understand the ramifications of their personal data ending up in the wrong hands. Reading your question again, I don't think children need a higher standard of privacy than adults - rather, I think the point is that regardless of the standard of privacy, children can only give limited consent.