Error when trying to access model's parent.

Are you sure "student_id" is the foreign key? I had a similar problem
the other day.

A one-to-many relationship is set up as so:

class StaffMember < ActiveRecord::Base
  has_many :students

class Student < ActiveRecord::Base
belongs_to :staff_member

belongs_to( ) declares that the given class has a parent relationship
to the class
containing the declaration - so staffmember is the parent of student

Your student table needs to have a foreign_key called: staff_member_id

I would change your controller as such, so that the logic is in the
controller and not the view:
@student = Student.find(params[:id])
@staff_name = @student.staffmember.first_name

Then in your view
<%= @staff_name%>

Hope this helps -K