.. _Cohorts Overview:

##########################################
Using Cohorts to Build Course Communities
##########################################

Cohorts create smaller communities of students within a course. Students who
are in a cohort can communicate and share experiences privately within course
discussion topics.

When you enable the cohort feature for your course, the discussion topics that
you include in units by adding discussion components are divided by cohort.
This means that each post that a student makes to those content-specific topics
can only be read, and responded to, by members of the same cohort. However, any
course-wide discussion topics that you set up for your course remain unified.
This means that all posts can be read, and responded to, by every student. You
can change some, or all, of your course-wide topics to be divided by cohort.
See :ref:`Options for Discussion Topics`.

This section also describes your options for :ref:`assigning students to cohort
groups<Options for Assigning Students to Cohorts>`. When you enable the cohort
feature, you define a set of cohort groups to reflect communities of students,
and select a strategy for assigning students to those groups. Note that:

* Every student must be assigned to a cohort group. This assures that every
  student has the ability to read and contribute to all of the course
  discussion topics.

* Each student is in one and only one cohort group. 

To provide a consistent experience throughout the course run, each student's
assignment to a cohort group should remain unchanged after the course begins.

For more information, see:

* :ref:`Enabling and Configuring Cohorts`

* :ref:`Moderating Discussions for Cohorts`

For information about discussions, see :ref:`Discussions`.

.. _Options for Discussion Topics:

*********************************
Options for Discussion Topics
*********************************

By enabling the cohort feature in a course, you provide students with the
ability to ask questions of, and have conversations with, other members of
their cohort. By offering cohort-only discussion oppotunities, the cohort
feature can help students develop a sense of community, provide specialized
experiences, and encourage deeper, more meaningful course involvement.

Enabling the cohort feature has different effects on the course-wide discussion
topics and the content-specific discussion topics in the course.

===================================================
Course-Wide Discussion Topics Are Configurable
===================================================

To create course-wide discussion topics, you add them on the **Advanced
Settings** page in Studio. By default, each of these topics is unified. All of
the students in the course can post, read, respond, and comment in course-wide
discussion topics without regard to their cohort group assignments. After you
add a course-wide topic, you can configure it so that it is divided by cohort
instead.

For example, in addition to the General topic, which is supplied by default,
you create these additional course-wide topics: Course Q&A, Announcements, and
Brainstorming. You want all students to be able to read and contribute to all
of the posts in the General and Course Q&A topics. However, you want the
Announcements and Brainstorming topics to be divided, so that students will
only be able to read and respond to contributions by the members of their own
cohorts. You complete the additional configuration step for the Announcements
and Brainstorming topics only.

For information about course-wide discussion topics, see
:ref:`Organizing_discussions`. For information about configuring these topics, 
see :ref:`Configure CourseWide Discussion Topics as Private`.

===================================================
All Content-Specific Discussion Topics Are Divided
===================================================

Each of the content-specific discussion topics is divided by cohort. A student
who is assigned to one cohort group cannot read or add to the posts, responses,
or comments contributed by the members of another cohort group.

To create content-specific discussion topics in a course, you add units that
include discussion components. In a course with the cohort feature enabled, you
do not have the option to change these topics to be unified for all students.

For more information about content-specific discussion topics,
see :ref:`Organizing_discussions`.

.. _Options for Assigning Students to Cohorts:

***********************************************
Options for Assigning Students to Cohort Groups
***********************************************

You can configure the cohort feature so that students are assigned to cohort
groups automatically or manually. You can also use a combination of both
assignment methods. Typically, your purpose in including the cohort feature in
your course determines which assignment option you will use for your course.

* :ref:`All Automated Assignment`

* :ref:`All Manual Assignment`

* :ref:`Hybrid Assignment`

* :ref:`Default Cohort Group`

.. _All Automated Assignment:

=============================================================
Making MOOC Discussions Manageable: Automated Assignment
=============================================================

In very large courses, the number of posts made to course discussion topics can
make for a daunting amount of daily reading. In such courses, dividing the
enrollees into separate cohorts makes the volume of posts, responses, and
comments by the members of each one more manageable, and is more likely to
foster community feeling.

To implement this assignment strategy, you enable the cohort feature and create
a set of "auto" cohort groups. The first time a student views the course
**Discussion** page or any of the content-specific discussion topics, he or she
is randomly assigned to a cohort group. Together, all of the students assigned
to a group are a cohort.

These guidelines, which are based on the experiences of MOOC teams that have
used the cohort feature in this way, are suggested to help you determine how
many auto cohort groups to define for your course.

* Each cohort should be large enough to inspire lively participation and
  diverse points of view, but small enough to allow a sense of community to
  develop. Cohorts formed by random assignment tend to be successful if they
  include between 200 and 500 members.

* For every 10,000 students who enroll, approximately 200 to 400 students
  remain active in the discussions throughout the course run. 

* Divide the estimated total enrollment of the course run by 10,000.

* Use the result as the number of auto cohort groups to create.

For example, two days before it starts, a course has an enrollment of 80,000
students. To create small communities within the discussions, the course team
enables the cohort feature and creates eight auto cohort groups. As they visit
the **Discussion** page and view the discussion components in the course
content, students are assigned to one of the cohorts. In divided discussion
topics, students read and respond to contributions made by other members of the
same cohort only.

For more information, see :ref:`Implementing the Automated Assignment
Strategy`.

.. _All Manual Assignment:

==========================================================
Grouping by Common Characteristic: Manual Assignment
==========================================================

In SPOCs and other courses with small- to medium-sized enrollments, known
existing commonalities can be used to identify cohorts. An example is a course
that enrolls students from different companies or with different educational
backgrounds, or members of alumni or parent groups. When students are assigned
to cohorts on the basis of a characteristic that they share, they can privately
discuss applications for what they are learning and explore resources and ideas
that are of particular interest.

To implement this assignment strategy, you identify the "real-world" cohorts
that your students belong to already. You enable the cohort feature and create
a "manual" cohort group to represent each of those cohorts. You then assign
each student to one of the manual cohort groups. Every student who enrolls,
including those who enroll after the course starts, must be assigned to a
cohort group.

.. note:: To ensure that every student is assigned to a cohort group, you can 
 set up a single auto cohort group, as described for the :ref:`hybrid
 assignment strategy<Hybrid Assignment>`. If you do not create an auto cohort
 group, the system automatically creates a :ref:`default cohort group<Default
 Cohort Group>` and assignes students to it if necessary.

For more information, see :ref:`Implementing the Manual Assignment Strategy`.

.. _Hybrid Assignment:

=============================================================
Accomodating Small Groups Within a Course: Hybrid Assignment
=============================================================

For some courses, the manual assignment strategy isn't feasible to execute, and
the automated assignment strategy doesn't accommodate the existing cohorts that
exist in the student body. The enrollment may be too large to complete manual
assignments effectively, or only some of the students may have strong defining
characteristics among an otherwise diverse student body. For these courses, you
can use a hybrid of the two strategies to implement the cohort feature.

An example is a course that enrolls members of an alumni association. The
alumni want an opportunity for private interactions, so manual assignment of
those students to a cohort group makes sense. For other students in the class,
manual assignment isn't needed: you create one or more auto cohort groups for
those students.

Before you implement the hybrid strategy, you identify the characteristics that
define existing cohorts in the student body. You also decide whether you want
the rest of the students in the course to be divided into their own, 
similarly-sized cohort groups, or if you want them all to be in just one other 
group.

After you enable the cohort feature, you create a manual cohort group for each
cohort that you identified. You manually assign students who belong to those
cohorts to the corresponding groups. You also set up auto cohort groups for
the other students in the course, or rely on the default cohort group. The
students who are not assigned to a manual cohort group are automatically
assigned to one of the auto cohort groups, or to the default cohort group if
you choose to use it, when they view the **Discussion** page or a discussion
topic in the course content. (For best results when you use this strategy, you
complete all manual assignments before the course starts and students begin
viewing discussion topics.)

For more information, see :ref:`Implementing the Automated Assignment
Strategy` and :ref:`Implementing the Manual Assignment Strategy`.

.. _Default Cohort Group:

==================================================================
Assuring That All Students Are Assigned: The Default Cohort Group
==================================================================

In a course that has the cohort feature enabled, all students must be assigned
to a cohort group. To assure that all students are assigned, the system
automatically creates a default cohort group and assigns students to it if
necessary. Creation of the default cohort group only occurs if you do not
define any auto cohort groups for your course. Any student who is not assigned
to a manual cohort group is assigned to the default cohort group automatically
when they visit the **Discussion** page or a discussion topic in the course
content.

Students who are assigned to the default cohort group see a cohort name of
"Default Group" in discussion posts. 

.. image:: ../Images/post_visible_default.png
 :alt: A discussion topic post with "This post is visible to Default Group" 
       above the title

If you want students to see a different cohort name when your course starts,
you can add an auto cohort group with the name that you prefer. See
:ref:`Define Auto Cohort Groups`. (Adding an auto cohort group to your course 
for this purpose is not recommended after your course starts.)

You can check the :ref:`student profile information report<View and download
student data>` for your course to see if any students are assigned to the
default cohort group in your course, and change their group assignments. Note,
however, that in divided discussion topics students can only see posts by
members of their currently assigned cohort group: when a student is reassigned,
posts "disappear". As a result, any group assignment changes should be done as
early in the course run as possible so that students see discussion posts and
contributions that remain consistent over time.
