L21 is a Web 2.0 social classroom environment.

Teachers and students can create "Lesson Books" that can cover any topic.

Teachers can create quizzes at the end of Lesson Books. A variety of question types are available, from true and false, multiple choice, which are scored automatically, to essay answers, which can be evaluated and graded by the teacher.

Everyone can post facebook-like status updates so everyone can communicate in the classroom the way they are used communicating outside of class.

Another feature is the Forum, which can be used by the teacher like a virtual classroom. It is also the place where students can ask questions and the teacher and other students can help to answer those questions.