State regulations permit teachers to be assigned no more than one period a day outside their certification, license/appointment area when no certified or qualified teacher is available. This is called incidental teaching.
However, a superintendent of schools may assign certified teachers to teach a subject not covered by their certificate for a period not to exceed ten classroom hours a week when no certified or qualified teacher is available after extensive and documented recruitment. Please note that teachers who do not hold special education certification cannot have incidental teaching assignments where special education certification is required.
Additional information about incidental teaching can be found on the NYSED website.