This is a really cool website, and I can't say enough about it! I discovered this at a training that I went to in May, and I can't wait to start using it.
Once you sign up, your classroom is created. You can then create quizzes that are multiple choice, true/false, or free response. During your lesson, you provide the students with the link and your classroom number, start your quiz and the students are then able to enter their responses to your quiz.
The site lets you track progress of completion, see responses, and even download the data into Excel. This is a great tool that you can use as an exit ticket, or as a morning station. You can even have groups of students "race" against each other in teams.