Tennessee

There are many factors (including teacher efficacy) that impact student progress. Public schools are funded through property taxes. Some districts are richer than others, and those districts have better facilities and more resources. And of course, some kids are more privileged than others and can focus more on schoolwork and less on simply surviving the day. They have broadband internet, multiple devices, parents who have more time to help them, and money for tutors when high stakes tests are coming up.

The mathematician's formula is reductive and facile at best, and it does a disservice to children.