A rule of thumb is:

If a theory appears in college textbooks, it may not be mature, or even correct. 

If a theory appears in senior high textbooks, it should be mature, widely accepted, and very probably correct. 

If a theory appears in K-12 textbooks, then it should be a done deal. 

The only exception that I can think of is the Newton laws of gravity. It's in high school physics textbooks, and we all know it's wrong. But we still teach it to the kids because the concept is easier to grasp and the equation is so simple yet accurate in most instances.