I would like to start this with some students who are struggling, my question is do they have to have their own id?
It's my understanding that in order to be tracked, or maximize the power of Khan Academy, that a participant does need to sign in with an email address. But, I have seen it used successfully in an environment where kids do not sign in. It allows for students to choose which lessons to view and practice, which has proved to be beneficial for some students that need enrichment, as well as remediation. They still need to be monitored and directed in order to make appropriate choices, but I believe it is a very useful tool if it is used in addition to classroom lessons and support. It has also been helpful to me with providing parents additional resources their kids can utilize at home or while they are out sick or on vacation, etc.
I don't use it on a regular basis, but they need either to log in with their facebook account or gmail account. Keep in mind that facebook is often blocked at school, so gmail would be the way to go.
Once they have logged in, they connect their account to yours.