Complex data model for new "Classroom" addition to the app. Requires using a intermediary relationship table to achieve the necessary abstract-ness.

models.py

class Classroom(models.Model):
    name = models.CharField(max_length=100)
    code = models.CharField(max_length=10, unique=True, default=_create_small_code)
    students = models.ManyToManyField(WUser, through='Attendance')
    creation = models.DateTimeField(auto_now_add=True)

    def __unicode__(self):
        return self.name

    def class_code(self):
        full_code = "%s-%s" % (self.name, self.code)
        return slugify(unicode(full_code)).__str__()


class Attendance(models.Model):
    user = models.ForeignKey(WUser)
    classroom = models.ForeignKey(Classroom)
    instructor = models.BooleanField(default=False)
    date_joined = models.DateTimeField(auto_now_add=True)

    def __unicode__(self):
        return "%s in %s" % (self.user, self.classroom)