One is likely to mistake Odoos technical models for directly fulfilling business needs. The models actually enable to add capabilities to business objects, by eliminating the need of building them by hand.
Odoo's email and messaging system, called Chatter system, is one the brilliant examples of these. It allows to add notifications and discussion threads to any model. In order to to display the discussion thread, the model simply has to _inherit mail.thread, and add the message_ids field to its form view. Discussion threads are per-record.
If you want to discussions and notifications in OpenERP(Odoo) paste the below mentioned code in your model.py file -

model.py
  class Courses(models.Model):
    _name = 'academy.courses'
    _inherit = 'mail.thread'

    name = fields.Char()
    teacher_id = fields.Many2one('academy.teachers', string="Teacher")