According to lots of recent stories and year-end reviews, Chromebooks are outselling everything edtech related from Apple and Microsoft in American schools.

So, are Chromebooks popular because they are superior to iPads as instructional tools? Because they offer students more learning tools than the Surface? Because they provide better creative opportunities than Windows or Mac laptops?

Of course not.

School districts covering 4 million students in 36 states were required to implement Common Core online testing in 2014, and for many districts, Chromebooks were able to do the job at the right price. The two main organizations that manage online testing in the United States, PARCC and SBAC, both require testing devices to have a keyboard. “While Apple devices can be used with Bluetooth keyboards, online testing requirements have favored Chromebooks,” Futuresource analyst Mike Fisher told Fortune.

$200 devices that can be used for standardized testing. That restrict students from doing anything that doesn’t come through a browser. Devices that are easy for the adults to manage. What’s not to like?

Yep, schools are buying boatloads of Chromebooks because they’re good for the kids.