When installing Lubuntu-Installation the first user created is labdoo (who is also administrator and should be reserved for the teachers, as this user may destroy the system by mistake). If you install via cloning or if you use the installation scripts the additional user student will be created automatically.
The user student kas less rights, e.g. is not able to install or delete software and is not able to destroy the system.
Here is the manuel way, how to create a user student: