django no such table:

I have models in Django set up as below.

class Pupil(models.Model):
    forename = models.CharField(max_length=30)
    surname = models.CharField(max_length=30)
    dateofbirth = models.DateField()
    year = models.IntegerField()
    class_group = models.CharField(max_length=30)
    email = models.EmailField(blank=True)
    assignments = models.ManyToManyField('Assignment', verbose_name='related assignments')

    def __unicode__(self):
        return u'%s %s' % (self.forename, self.surname)

class Subject(models.Model):
    name = models.CharField(max_length=30)
    level = models.CharField(max_length=30)
    teachers = models.ManyToManyField('Teacher', verbose_name='related teachers')

    def __unicode__(self):
        return self.name

class Teacher(models.Model):
    forename = models.CharField(max_length=30)
    surname = models.CharField(max_length=30)
    email = models.EmailField(blank=True)

    def __unicode__(self):
        return u'%s %s' % (self.forename, self.surname)

class Assignment(models.Model):
    assignment_name = models.CharField(max_length=30)
    date_assigned = models.DateField()
    date_submitted = models.DateField()

    def __unicode__(self):
        return self.assignment_name

When I attempt to add a pupil and attach an assignment to the pupil in the admin, I get a database error -

no such table: homework_pupil_assignments

after reading this I realised this could be due to django not updating changes to my models as when I do manage.py sqlall homework

I see the following:

BEGIN;
CREATE TABLE "homework_pupil_assignments" (
    "id" integer NOT NULL PRIMARY KEY,
    "pupil_id" integer NOT NULL,
    "assignment_id" integer NOT NULL,
    UNIQUE ("pupil_id", "assignment_id")
)
;
CREATE TABLE "homework_pupil" (
    "id" integer NOT NULL P