Whiteboard Chat is an interactive website which is used to create boards for the entire classroom and watch the work of the students in real time. It is free, and up to 100 people can connect to a board at the same time, the work done can be exported in PDF. This is a very useful tool for syncronous learning, because it gives teachers the possibilty to observe the work of all their sudents at the same time, thus it recreates the atmosphere of a lesson in presence.
Whiteboard Chat can be used without an email address which makes it quicker and easier to get started. All you have to do is simply to send the link to students.