The document discusses the challenges and methods of mobile language learning, particularly English, emphasizing the need for an engaging and effective approach suitable for smartphones. It highlights a study conducted with Japanese high school students comparing vocabulary acquisition through paper books, e-books, and an adaptive learning device, revealing no significant difference in learning effectiveness among the methods. The authors conclude that while no particular technology was shown to enhance incidental learning, ongoing developments like the new Elmo device aim to improve the learning experience.