Rafael Martinez

In our dojo we have a simple etiquette for this situation. First you must understand that the chief instructor asked a specific person to teach. He or she must have a reason for doing so. Whatever the reason all students should respect that decision. So on the day of the class if a higher ranking student arrives the lower rank out of courtesy will ask the senior ranking student to teach. The proper response from the higher ranking student is to decline. This acknowledges solidarity with the chief instructor and promotes harmony within the dojo, the forms have been followed. We also make it a point to only ask the senior most student. This offer is only made to one person for that day. Otherwise we would be working our way down the line.
Finally, it is understood that if the senior student decides to take the class he will have to answer to the chief instructor and explain why he went against his directive.
I hope this helps.