Unqualified public school teachers cheated on tests to get teaching jobs

It would be interesting to see if the teachers who cheated to get these jobs did as well career wise as those who didn't.  How could 60 some teachers being admitted over a 15 year period of time effect only  hundreds of students?  Surely, the number must be in the many thousands.  Take a high school teacher.  Even if the person only had three classes with 20 each per semester, that would come to a minimum of 120 students per year.  Just 10 high school teachers for only one year would be over 1,200 students.  Without trying very hard it seems as if you would easily be in the 5-digit range.  From Fox News:

. . . For 15 years, teachers in three Southern states paid Clarence Mumford Sr. -- himself a longtime educator -- to send someone else to take the tests in their place, authorities said. Each time, Mumford received a fee of between $1,500 and $3,000 to send one of his test ringers with fake identification to the Praxis exam. In return, his customers got a passing grade and began their careers as cheaters, according to federal prosecutors in Memphis. 

Authorities say the scheme affected hundreds -- if not thousands -- of public school students who ended up being taught by unqualified instructors.  

Mumford faces more than 60 fraud and conspiracy charges that claim he created fake driver's licenses with the information of a teacher or an aspiring teacher and attached the photograph of a test-taker.  . . . 

The hired-test takers went to testing centers, showed the proctor the fake license, and passed the certification exam, prosecutors say. Then, the aspiring teacher used the test score to secure a job with a public school district, the indictment alleges. . . .