Vijay,
Thanks for bringing this up. Just so you know, when we started WiZiQ and all along its development, this is one thing we wanted to make super simple. Which is why we decided to go with a unique URL approach for each class.
Although as you mentioned it is pretty easy to get in the class, we see that a few students still have trouble and we have seen the following reasons for that:
1. Since we are dependent on e-mail for sending class invites, a few of the invites go in junk folders and so some students say they didn't receive them at all. All we can do is comply with junk mail guidelines and have to leave the rest to the recipient of the mail - he can check his junk folder, mark WiZiQ e-mails as 'Never send to Spam' etc.
2. Students have signed up with one e-mail account but receive class invites on another e-mail address and so get some security message. We are trying to solve this problem with alternate e-mail addresses.
3. The students get lost on some other page in WiZiQ, say watching a tutorial and so they can't find their class. We are trying to solve this with our dynamic home page which will remind the user where his latest upcoming class is.
And BTW, we are coming up with a new version of class scheduling and attending module in about 6 weeks that will solve the problems I mentioned above and we will also add the 'Attending a WiZiQ Class' tutorial on the class page.