Apple Inc. on Thursday launched its attempt to make the iPad a replacement for a satchel full of textbooks by starting to sell electronic versions of a handful of standard high-school books. The electronic textbooks, which include "Biology" and "Environmental Science" from Pearson and "Algebra 1" and "Chemistry" from McGraw-Hill, contain videos and other interactive elements. 

The printed books are bought by schools, not students, and are reused year after year, which isn't possible with the electronic versions. New books are subject to lengthy state approval processes.

All this means textbooks have lagged the general adoption of e-books, even when counting college-level works that students buy themselves. Forrester Research said e-books accounted for only 2.8 percent of the $8 billion U.S. textbook market in 2010.

Pearson PLC of Britain and The McGraw-Hill Cos. of New York are two of the three big textbook companies in the U.S. market. The third one, Boston-based Houghton Mifflin Harcourt, also plans to supply books to Apple's store, but none were immediately available.

The new textbooks are legible with a new version of the free iBooks application, which became available Thursday.

The textbooks will cost $15 or less, said Phil Schiller, Apple's head of marketing. He unveiled the books at an event at New York's Guggenheim Museum. Schools will be able to buy the books for its students and issue redemption codes to them, he said. It wouldn't work to let students who can afford to buy their own iPads use them in class with textbooks they buy themselves, alongside poorer students with printed books. 

According to biographer Walter Isaacson, reforming the textbook market was a pet project of Apple co-founder Steve Jobs, even in the last year of his life. At a dinner in early 2011, Jobs told News Corp. chairman Rupert Murdoch that the paper textbooks could be made obsolete by the iPad. Jobs wanted to circumvent the state certification process for textbook sales by having Apple release textbooks for free on the tablet computer.