With the iPad, yes. Though we could see that change with the cheaper Android tablets like the Nexus. School districts these days are pressed for cash.
As far as Macintosh computers go, at least in the districts I grew up in ( all of which had zero money problems, I think mine actually had a problem with to much money, so they randomly renovated the entire high school campus for 54 million, even though the buildings were only 15 years old ) were a very rare sight, you saw some older ones in the kiddie labs, and a couple G3 laptops. But everything was Dells and Compaqs.
I've been to the local high school before helping out a friend ( he's an basic computer science teacher, ugh ). And it was all a sea of dells. According to him at least, the Mac is leaving the K-12 market due to extreme cost. Look at it from their perspective, you can buy 3 Dells for the price of one Mac,( they refuse to go Mini, they iMac the macs they do have. They buy 300 dollar Dell mini towers, with 16 inch monitors, and I think they get a HUGE discount on the monitors. ) and Dell has a better warranty than Apple. And the Dell can be repaired in house, the Apple cannot. They do have a large number of iPads however, and Apple is probably going to be strong in that market for a long time,
However, Apple probably is at its peak, its not a computer company anymore of course, it's going down the same path SONY did. It'll be the name brand to buy for awhile until someone else comes along. Its just the way things go.
I don't understand all these " Apple is doomed! " Threads, they'll be fine. But they are at the point where there are a group of people who just will buy an ' i ' device no matter how good or bad it is.