The greatest shortcoming of the [school] districts is their failure to recognize that they must be responsible for the training and monitoring of teachers. Nearly every school district suggests that any new teacher must be able to "adjust instruction so that it is appropriate for individual students." Yet, this ability is never tested, and the district has virtually no capacity to induce it in the teachers who can't do it (which would include the vast majority of teachers). We have analyzed the skill level of teachers in typical school districts, and the results are appalling. The teachers typically know very little about the instructional programs that they use, have a very vague understanding of students' skill level or ability to perform on the topics that are "taught," and teach in a way that is not well designed to transmit information to the average student. Despite their skill deficiencies, however, the teachers are not monitored or trained. Furthermore, the diagnostic procedures used by the schools are designed to protect the teachers. A district may have file cabinets full of records of students who failed because these students are assumed to have problems, such as "dyslexia." In contrast, there is usually not one folder on a child who failed, not because of a child problem, but because the teachers failed. The probability of such a distribution is very suspect.
Engelmann, Advocacy For Children, 1982