Classmates publishes lists of children by name and school. Not as an accusation, as a description of what loads. Walking the site without an account reaches an Alumni List for any school it holds, giving each person's name and the years they attended, and the schools include elementary ones.
The yearbooks sit behind that. A yearbook was a printed book handed to pupils at the end of a school year, and nobody in it had any way to anticipate it being scanned, indexed and made searchable decades later. That gap between what was agreed to in 1994 and what exists now is the whole of the legal problem below.
The practical consequence is that Classmates holds a category of information none of its sibling brands does. Intelius, TruthFinder, Instant Checkmate and US Search publish records assembled from public sources about adults. Classmates publishes school rolls and photographs, and it does not restrict itself to people old enough to have consented to anything.
It is also the odd one out administratively. The other brands appear on California's data broker register under their own names, Intelius, LLC and Instant Checkmate, LLC among them. Classmates does not appear at all.