Zoom call participant grid placement and appearance

I have a virtual class when classmates are signed on and enter the meeting we are all displayed in a grid formation.  The teacher is always top upper left, (on my screen) I am always situated next to him.  I never move down into the grid, switch rows, move further left or right etc.  other classmates seem to bounce around in their placement.  But I always occupy the position next to the teacher.  What are the dynamics going on here?  Do others see a similar placement on their screens?  Does what I see and static placement have to do with my settings?  Is the teacher controlling this?