Re: New dojo/new student
What would you normally do in your dojo if you were teaching and new students came to class?
In our dojo with brand new people we usually start with rolling and tai-sabaki, perhaps an exercise demonstrating some 'building block' movement used in many techniques (for example blocking and stepping off the line), and then one or maybe two fairly 'simple' techniques (simple in the sense of there not being many steps or hand changes), sometimes using the tai-sabaki or blocking we already looked at.
Of course if you have several new students and no senior students to help you and lead by example then you'll also have to spend a moment or two explaining etiquette like when to bow, lining up, when to sit seiza, etc.
Depending on how many students show up, I'd probably try to think of things you can explain in pretty simple steps as they will all be working with another new person in paired practice (so not as much one-on-one help as new students get in a mixed class), and you will have to demonstrate on a new person as well.