Students can sign up and use XtraMath regardless of whether or not their teacher uses the Web program, but they need to get the approval of a parent to do so. Students cannot set up accounts on their own, and they need to set up an account to sign in.
The usual route for signing up for XtraMath involves using the enrollment code given on a flier handed out at school, but parents can also sign up their children on their own. Either way, parental participation is required, as school enrollment of a student requires a parent's email. Once set up is completed, students may sign in whether or not they are part of a formal school program that uses XtraMath, but parent and teacher accounts are used to track progress, so some involvement from an outside party is still required.