private bool DoesThisEmailExist(Teacher aTeacher)
{
List <string> emails = new List <string>();
aTeacherGateway = new TeacherGateway();
emails = aTeacherGateway.GetAllEmails();
foreach (string email in emails)
{
if (email == aTeacher.Email)
{
return(true);
}
}
return(false);
}