Infuse Learning is free to sign up and students do not need a login. It is similar to Kahoot but you have the ability to view student responses and show them on the projector through your computer (and also save responses). It can be done from the iPad, and there is no app to download, students just type in the address:
and then just type in your class number. The best part about it for me is that you can have students show their work or drawings, submit it to you and then you can show them to the class and also save their responses. You can also save the responses to look back at.