Three years http://ettchokladeri.se/aaamedicaltestingcom-205e.pdf upmchealthsecurity.org  Cohen and Duncan highlighted how access to digital textbooks allows for more "vibrant and understandable" lesson plans that ultimately allow school systems to save money. "What's fascinating to me is that we are still spending $7, $8, $9 billion a year on textbooks. Beyond that, we have states that are on seven-year textbook adoption cycles," Duncan said. "We know information is changing by the minute, so the fact that we are spending so much money on something that is so outdated makes no sense to me whatsoever."