Lloyd Lofthouse

In the Vergara trial, the judge’s verdict was based on unproven theories that a few incompetent teachers would ruin a child’s ability to earn an education. The numbers presented in one theory were one to two percent of teachers might be incompetent—not “are incompetent” but “might be incompetent” because of classroom observations of one man over a period of several years.

The judge should have asked for details. For instance, how many teachers can one person observe long enough to form a valid judgment, and how long was each observation? What if a teacher considered incompetent was having a bad day and the other 179-instructional days that teacher was competent?

Anyway, let’s look at a few numbers based on the 2011-12 school year in California:

There were 6,220,993 students enrolled and attending 10,296 public schools in California. Another 438,474 students attended 1,019 Charter schools.

There were 300,140 teachers in the…