LearnEnglish, produced by the British Council, offers a variety of exercises and games for children, teens and adults. Another popular option is Duolingo, which hosts a number of interactive exercises and generates new ones based on online documents.
The LearnEnglish websites only offer lessons for the English language, which allows it to provide carefully crafted lessons. Some of its exercises are also designed for children, who often have short attention spans. Duolingo offers instruction for a number of languages, but the inventive portion of the site is asks users to translate texts between their native languages and target languages. As a result, the website's users, while learning foreign languages, create new exercises for other users.