As the erroneously attributed quote not made by Senator Dirken goes: a billion here, a billion there, pretty soon it adds up to real money.
iPad do not make better students. Better teachers make better students. Start there. Technology has been in U.S. classrooms for decades. When I was a grad student I was involved in a program in a DC high school that had the highest % of underprivileged kids in the metro area. The school had an amazing array of computers and even a mini TV studio. It still had more drop outs than graduates; more failing students than ones that were even eligible to get into the lowest ranked junior college. Most of the teachers gave up and were mostly baby sitters.
My point: if you want to understand the public education problems in the country, tech is not a quick fix nor is spending money. The issues are much deeper, and, unfortunately, very political, in just about every sense of the word. Understand the DC, for example, which has one of the worse school systems in the country -- the president, congressmen and women, and senators won't send their kids there -- spends $18K per student. The national average is around $10K per student.