Salary chart interpretation: "M.A" vs "60 Units includes MA" vs "M.A. plus 35 Grad Units" For the record, I'm a college dropout myself... ;-)

During the late 90's, my wife completed both a B.A and M.A.  in Psychology in the Cal State system.   She also completed during the Master program two years of interning to concurrently obtain her required Certificate as an Educational Psychology.   She then essentially worked for the same employer for about 18 years.   However, she is ready to move on.

While assembling a comparison chart of salaries across districts, I was stumbling on one of them.  It features three separate charts, with the following labels which I am putting here verbatim:

I: "M.A." 

II: "B.A. + 75 Graduate Units Includes M.A  -OR- M.A. + 35 Graduate Units"

III: "60 Semester Graduate Units Includes M.A."

These have different significantly pay scales, with I: the lowest and III: the highest.

(There is an seperate addenum noting an additional stipend for a earned doctorate).

I guess I'm not clear on why so many charts?  What is meant by "60 Semester Graduate Units Includes M.A".    Why would this merit a higher salary?  Surely this doesn't mean 60 units AFTER completing an M.A.?  And why "B.A + 75 Includes M.A:?"   Clearly, I am not understanding the terminology.  (Again, dropout here).

This is just an academic exercise (groan, bad pun), since this is not a district she is likely to apply to, but we are trying to put together a comparison chart to see where each stands based on her years of service.
Are these public school districts?

 Interpreting Salary Tables

School districts often have different pay schedules, which is what you are seeing.  Although I'm not from California, I've seen quite a few of these in my own state.

"60 semester graduate units Includes M.A." likely means that she can count her M.A. credits as part of the 60 hour requirement. If her M.A. required 36 hours, she could qualify with an additional 24 hours.

I is the lowest pay scale because it requires the least number of credits. Think of it as MA+0 credits.  II is MA+35 credits; III is MA+60 credits.  Pay increases with additional coursework.

 The Rationale Behind These Tables

Primary and secondary teachers (and other staff, like counselors or behavioral specialists) often start their careers with a Bachelor's degree, which is required in most states for a teaching license.  

Additional education is desirable for teachers. It allows them to stay up to date on teaching techniques, expand their subject-matter expertise, earn additional endorsements or licenses, or earn higher degrees (which might include any of the previous reasons).  For example, a physics teacher who wants to expand into teaching biology might be required (by state law) to have a biology endorsement, which might take 12 credits to earn.

Since salary advancement is tied to having higher degrees and more college credit, it is not uncommon to see a teacher with an MA plus an additional 30-40 credits - if they are a career teacher.  These credits would have been accumulated over time, perhaps 1-2 courses a year, rather than the traditional college schedule of 4-5 courses at once. These credits may or may not be part of a degree program.  A Ph.D is less common, but does happen occasionally.