Ideally, we should speak in English always while in the classroom. That includes while arranging or organizing our class: making groups, getting material ready, giving instructions... Here you are some sentences you can use in your classroom.
Turn your chairs around and face the clock.
María, could you collect all the sheets and put/leave them on my table, please?
Make groups of four desks facing each other
Stand by your desks
María, would you mind coming out and writing it on the board?
I'm sure these sentences can be a good starting point. In case you need more help, you can have a look to the book I've used in this post.
You also can cast your eye over this table, made by me, with useful pairs of opposites you can use when organizing your classroom:
