After a minor student signs up for an account, their profile enters "Pending" status while it waits for parental approval (which is obtained through parent/guardian consent via email to parent).
To see which accounts are waiting for approval still and edit parental email addresses, you can click on "Manage Pending Students" from your classroom dashboard:
From here, you can resend all verification emails to parents:
Occasionally students enter the parent email incorrectly. You can also edit individual approval email addresses from this screen:
After editing, click to resend the verification email to the new address: