Many schools don’t give student email accounts or permit students to use email at school. However, many Web 2.0 sites require unique email addresses, which poses a challenge.
A pretty usable workaround for this is this Gmail trick. If your teacher gmail account is ksmith@gmail.com and a student uses the email address ksmith+bemerson@gmail.com, all email to that address will go to you at ksmith@gmail.com. That allows you to register students for services that require a unique and valid email without maintaining or needing to monitor an email account for them.
Workaround for student email