A few hours away, every student at Burlington High School near Boston will also start the year with new school-issued iPads, each loaded with electronic textbooks and other online resources in place of traditional bulky texts.

While iPads have rocketed to popularity on many college campuses since Apple Inc. introduced the device in spring 2010, many public secondary schools this fall will move away from textbooks in favor of the lightweight tablet computers. Apple officials say they know of more than 600 districts that have launched what are called "one-to-one" programs, in which at least one classroom of students is getting iPads for each student to use throughout the school day. Nearly two-thirds of them have begun since July, according to Apple.

Districts are varied in their policies on how they police students' use. Many have filtering programs to keep students off websites that have not been pre-approved, and some require the students to turn in the iPads during vacation breaks and at the end of the school year. Others hold the reins a little more loosely.

"If we truly consider this a learning device, we don't want to take it away and say, 'Leaning stops in the summertime.' " said Larkin, the Burlington principal.

And the nation's domestic textbook publishing industry, accounting for $5.5 billion in yearly sales to secondary schools, is taking notice of the trend with its own shift in a competitive race toward developing curriculum specifically for iPads.

At Boston-based Houghton Mifflin Harcourt, for instance, programmers scrambled to create an iPad-specific secondary school program starting almost as soon as Apple unveiled the tablet in spring 2010.

The publisher's HMH Fuse algebra program, which became available at the start of the 2010 school year, was among the first and is a top seller to districts. Another algebra program and a geometry offering are coming out now.

The HMH Fuse online app is free and gives users an idea of how it works, and the content can be downloaded for $60. By comparison, the publisher's 950-page algebra text on which it was based is almost $73 per copy, and doesn't include the graphing calculators, interactive videos and other features.

For a school that would buy 300 of the textbooks for its freshman class, for instance, the savings from using the online version would be almost $4,000.

Jay Diskey, executive director of the Association of American Publishers' schools division, said all of the major textbook publishers are moving toward electronic offerings, but at least in the short term, traditional bound textbooks are here to stay.  "I think one of the real key questions that will be answered over the next several years is what sort of things work best in print for students and what sort of things work best digitally," Diskey said. "I think we're on the cusp of a whole new area of research and comprehension about what digital learning means."