The text on the screen will always tell you what is going on. Remember you are in a Cyber world so use your imagination. Each MUD has its own rules but most will let you get a list of who is logged on and their location. Some MUSs allow users to adopt role-playing personas in the virtual world, while others require the use of real identities. Each MUD consists of a shared place, activities, and content that encourage interactions and collaboration.
Some MUDs are just for teachers or students.
Variations on the MUD theme include MOOs. That is a MUD that is Object Oriented or written with more powerful software that makes building starships and Galaxies easier and with a lot more reality. There is no real way to explain a virtual experience so this is one of thoes things in Cyberspace that you MUST do on your own. Fire up your shuttle craft and head out to explore. Your third graders could construct an Native American village or an ancient Egyptian city.