Activities 
Activity modules provide the main activities in course, such as Forums, Assignments, Quizzes and so on.
Join the discussions about activities in the General add-ons forum.
Sub categories
Assignment (26)
Different types of assignments
Different forms of assignment submissions (Moodle 2.3 onward)
Different forms of assignment feedbacks (Moodle 2.3 onward)
Assignment types (8)
Different forms of assignments to be graded by teachers (Moodle 2.2 and earlier - /mod/assignment)
Database (4)
Plugins for the database activity module
Database fields (2)
Databases can be extended with new field types
Database presets (2)
Database settings, templates etc can be saved as presets
Workshop (3)
Workshop has a number of plugin types
Change how grading is allocated
Change how grades are evauated
Grading forms for workshop
Quiz (93)
Ways to extend quizzes
Quiz reports (6)
Quiz reports show results and statistics
Question types (56)
New types of questions
Question formats (10)
Question formats for import/export
Question behaviour (12)
We question your behaviour!
Plugins for controlling access to quizzes
SCORM (1)
New reports for SCORM
Book (4)
The book activity that is in core. It can have sub-plugins.
Book tools (4)
sub-plugins for the book activity module
LTI (0)
Integration with external tools via IMS Learning Tool Interoperability standard.
LTI sources (0)
LTI providers can be added to external tools easily through the external tools interface. This plugin type is specific to LTI providers that need a plugin that can register custom handlers to process LTI messages.
LTI services (0)
Allow the implementation of LTI services as described by the IMS LTI specification.