But mobile phones stand apart in an important way. In United States high schools, 98% of students have access to some kind of smartphone, according to a report by Blackboard and Project Tomorrow.

The United Nation’s International Telecommunication Union estimated that there were 5.3 billion mobile phone subscriptions worldwide at the end of 2010 — and that a full 90% of the world population now has access to a mobile network. In contrast, only about 2 billion people have Internet access.

Students around the world are increasingly bringing their own mini-computers (or some connected device) to class. Whether this creates a distraction or a boon to learning is debatable, but these four uses of mobile phones in education — and countless others — could one day help prove the latter.

1. Inquiry-Based Learning

Abilene Christian University (ACU) began equipping its students with iPods and iPhones in 2008 (now students can also choose an iPad).

Faculty have used the presence of phones in their classrooms in numerous creative ways. The theater department put on an interactive production of Othello, the student newspaper launched an iPad version and teachers have used phones to facilitate discussions on controversial topics.

The phones have also helped create a teaching style that the faculty refer to as "mobile-enhanced inquiry-based learning" — combining mobile phones and a learning theory that teaches through experimentation and questioning.

“Most students don’t really have a foundation that allows them to know what questions to ask," says Dwayne Harapnuik, director of faculty enrichment at ACU. "[The phones] transfer to a model where students access the information when they need it and then make more meaningful connections based upon what they already know."

Professors use the phones to deliver information, flashcards, key words and other basic information that students need in order to come to class ready to discuss and experiment. The project recently won a nearly $250,000 grant from Next Generation Learning Challenges to test the method at Del Mar College and California University of Pennsylvania as a way of reducing dropout rates.

2. Flipping the Classroom

In many ACU classes, one component of mobile implementation is lecture podcasts, which allow students to consume much of the information typically delivered in the classroom on their own time and in their own dorm rooms.

The idea is to free up teachers during class time for interacting with students and working through problems, a concept known as "flipping the classroom."

It also allows students to pause and repeat information that they find confusing, and they can work at their own pace.

Flipping the classroom is certainly possible without putting a mobile device in the hands of every student, and many universities — including UC Berkeley and MIT — have long made lectures available online, but Harapnuik says that doing so with a mobile component is an advantage.

"Do you ever leave the house without your phone?" he asks. "The beauty of a mobile phone is that it's always there."

In studies of the program, students who participated in an ACU class that used the mobile-teaching method performed modestly, but not significantly, better than their peers in a control class. On the other hand, the mobile-using group reported that they had learned more than the control group reported they had learned.

3. Reinventing the Textbook

"Textbooks are always the wrong information, in the wrong order, at the wrong price, at the wrong weight in my backpack," says Jed Macosko, an associate professor of physics at Wake Forest University.

Macosko is the co-founder of a project that aims to transform the textbook so that it complies with How People Learn (literally, it's inspired by a book of that title).

The result thus far is BioBook, a device-agnostic, peer-written, node-driven text. In other words, it's like Wikipedia on steroids.

In his classes, Macosko asks his students to write short one-concept nodes, which they then link with other nodes on the same subject. When a student opens the book, currently hosted on a wiki, he can click around the nodes to learn a subject in whatever order makes sense to him.

"It’s important to have the student engaged in connecting facts in a framework in their mind," Macosko says. "When you learn a fact, you basically hang it on a hook of some pre-existing structure in your brain.”

In a pilot project of the book, students preferred the book over their traditional textbooks (no assessments were taken to see if BioBook resulted in deeper understanding). A final version of the book, which will be piloted at four universities starting in September, will include analytics, multimedia, short quizzes and other options for teachers to interact with students.

That version will be device-agnostic.

"If you have this big heavy textbook, you don’t take it out of your dorm room very often," Macosko says. "But you might take your index cards out of your dorm room and use them to study for your next exam ... the same kind of portability of the index cards is what mobile will give you."

4. Teaching Hard-To-Reach Communities

In the report from the United Nation’s International Telecommunication Union, mobile penetration rates in developing countries were expected to reach 68% by the end of 2010.

The prevalence of mobile phones has led many education efforts to come to the same conclusion as Michael Trucano, senior ICT and education policy specialist at the World Bank.

"Broadband will come, but it will not come quickly enough. Computers, as we think of them sitting on someone’s lap or on a desktop, will come, but not quickly enough. Phones are already there ... We think there’s a real opportunity there to explore."

Trucano cautions that there aren't a lot of mobile education initiatives in developing countries that have reached scale. But there are several promising projects.

In Pakistan, for instance, one group of educators recently began experimenting with sending SMS quizzes to students. After the student answers a question, he receives an automated response, which varies depending on whether the answer was correct.

"For some of these students who have been educated in a system where very large, lecture-based classes are the norm, this may be the first time they have received 'personalized' feedback of any sort from their instructors," Trucano writes in a blog post about the project.

Others — like the text2teach program in the Philippines and the BridgeIT program in Tanzania — use phones to deliver educational video content to classrooms. The Human Development Lab at Carnegie Mellon University runs a program called MILLEE, which has used custom mobile games to teach language in India for the past seven years (the program has also expanded to rural China and sub-Saharan Africa).

"Especially at a time when many countries are considering buying tons and tons of computers to put into their schools — there’s nothing wrong with that but the fact that there is a huge installed userbase of people who have increasingly powerful computers — ministries of education should at least consider pocket computers part of their broader decisions about investment."