Ask any teacher -- a good substitute is worth his or her weight in diamonds and gold. And when retired teachers come back into the classroom as substitutes, they are usually the ones you want to get.

Especially since qualifications to work as a substitute are even lower than the pay for the work.

Qualifications for substitutes vary from system to system, with some requiring a bachelor's degree and others only a minimum number of college credits. The pay also varies, from about $75 a day to $103 for retired teachers.

My district does require some college to substitute -- a whole 30 hours of college credit. In other words, you can have kids who graduated the previous year coming back as substitutes if they took a couple of summer school classes and AP or dual-credit during their high school career. Fortunately, the district tries to keep them out of the high schools.

And don't fool yourself -- substitutes are a big expense for a district. Mine spent $1.7 million on subs last year -- for a variety of reasons, ranging from personal days and conferences to illnesses and maternity leave. And as it was, there were still classes that were covered by administrators, teacher, and even secretaries if there was no substitute available through our system.

Probably the best news I've gotten is that one of my recently retired colleagues is coming back as a substitute after a year of retirement. I know I will fight to schedule him into my class if i know in advance that I will be out of school.