If you're beginning with Moodle, you can usually practise drag and drop of resources or adding basic pages and URLs without the need to see how students interact with them. However, when you get to more advanced activities such as workshops or assignments, it helps your understanding to have some student input. The 'switch role to student' doesn't always display as you'd expect. You could ask your admin to make you a test student role, which is good, but most of us have more than one student in our classes, so that won't give a realistic picture of the gradebook.
Each Moodle resource and activity has a 'Using...' page in the docs and you'll often find, in the 'See also' section, a link to a working example. If you want to see a Lesson in action for instance, check out the Using Lesson documentation.
The Moodle School demo site, Mount Orange, has a range of pre-made activities you can try as a teacher (or student) Inspired by our Learn Moodle MOOC last September, there is a course on the School demo called 'Celebrating cultures' and here you will find a series of activities completed with student input. (OK maybe not real students but real fake students!)
Want to see how the assessment phase of a workshop works with actual submissions? Log in with the username 'teacher' and password 'moodle' and you can switch phases and experiment . Want to grade and annotate a pdf? Go to the assignment and practise on one of the uploaded student submissions. There are also a fully functioning and populated database and glossary.
Trying activities with student data gives you a much better insight into how they work, and allows you to troubleshoot any issues you might have on your own Moodle. And because, like our other demo sites, everything is wiped free on the hour, you can be as radical as you like!