It’s been more than a dozen years since the state launched the Maine Learning Technology Initiative — a program to put a laptop in the hands of every 7th and 8th grader across the state. The program has since expanded to high schoolers. And in 2013, it moved beyond laptops to touch-screen iPads. But now, some school districts say the iPad approach has led to software glitches, frustrated teachers and distracted students. As a result, some schools are switching back to laptops.