I find the Glossary to be a powerful tool. It is one of the under utilized activities.
The Glossary allows students to create a resource for the entire class. There are two broadly general types of activities in Moodle, those that are “private” between the student and teacher and those that are available for all the class to see. Assignments are generally private between a student and a teacher. The student completes the assignment and turns it in the teacher. The Glossary is very different in that the work that the students do is viewable by the entire class.
This is one of the great things about the Glossary module. It allows the class to create class resources. The Glossary Module allows the students to create a glossary of terms (pretty obvious). However, it can also be used in many more ways.