Obama is taking the old role of Father O'Malley by "dropping in" on the kids during class. With Obama's intentions of addressing students throughout the country on September 8th, two things come to mind: Communism 101, or the religious instruction given in parochial schools pre-Vatican II.
This is highly unusual for the President to assume a patriarchal role when he is an elected political official. Parents that are not followers of Obama's political persuasions will view this as threatening. Can you imagine the reaction if George W. Bush had addressed the students across America? It would have been inappropriate with Bush, and it is threatening and offensive as well for Obama to directly address the children of this country.
This is a primary facet of Fascism, and how it is historically known to present itself in the streets and throughout the community. What's the next step? Asking children to report their parents?