For everyone tripping about the price, as a teacher I can confirm that chrome books are not an 'in kind' substitute for iPads. Yes, they may (now) be $100 less for the bottom of the line....but you also get crap components, cheap flimsy plastic, keys that easily come off, and one drop destroys the screen (not the physical screen, but its functionality). They're cheapER, but beyond that that they're flat out CHEAP and low quality.
On the other hand, for $100 more you get an iPad that is an industry leading tablet, has the same build quality and construction (and many components) of the $600 model. Their usable life span may not be more than 6 or 7 years before they're just too outdated to work, but the physical usability of a Chromebook is a few years when they're being used by kids in school. Trust me, I know.
These are for districts that are probably smaller, are committed to eliminating textbooks and using digital or teacher created materials instead, and can justify an 8 year buy cycle by buying iPads, pencils, and cheap bluetooth keyboards instead of textbooks....which also have an 8-10 year refresh cycle and cost $200-$300 each. Plus, when you buy textbooks, you need one for each child in the district. Schools can get away with classroom sets of chrome books that lessen the cost anyway.