The list of explanations for why classroom practices, even when counting modest changes teachers made in routine tasks and activities, has remained largely stable over decades is hardly exhaustive or inclusive. It does, however, cover the major ones in the literature on school reform.

*What keeps teaching largely stable are teaching traditions dating back centuries that are reinforced by those who enter and stay in teaching, supported by popular social beliefs, and fortified by the age-graded school structure.

Historical traditions of teacher-centered instruction to transfer knowledge, skills, and values from one generation to another stretch back millennia.  Former students who decide to become teachers pick up instructional habits they saw in their teachers and then teach the next generation. Traditional forms of teaching persisted not only through habit but also because they were viewed as both efficient and effective.

Moreover since the nature of teaching is conservative—i.e., transmitting knowledge, skills, and values to the young—the occupation has attracted people who believed that such practices were not only socially responsible but also worked for them when they were students.

Furthermore, district and principal authority curb teacher authority outside the classroom.  No teacher, for example, can tell a student that the class is too large and must go to another teacher.  But not inside their classrooms.

Also limiting teacher autonomy is the age-graded school with self-contained classrooms, a curriculum delivered to students chunk-by-chunk, annual tests, and yearly promotion to next grade. This structure arose during the industrialization and urbanization of the U.S. in the 19^th and 20^th centuries and remains the dominant form for organizing schooling in the 21^st century.

Once teachers close their doors, however, district and principal authority is limited; the age-graded school structure permits a constrained autonomy. Teachers decide on which lessons they continue to teach and which they change. They decide to use old technologies and try out new ones. They experiment with new materials while using ones that had worked in earlier lessons. They engage students in familiar activities and switch to different ones they discovered or learned about. This age-graded structure permits limited autonomy for both stability and change to co-exist in the same classroom but at the same time isolates and insulates teachers from one another hampering collaboration across grades and departments.

Historic traditions of teaching renewed each generation by those who learned those traditions as students and now teach in age-graded classrooms are further fortified by popular beliefs held by large proportions of taxpayers and voters about teaching and learning in a “real school” (Metz real schools). Most Americans believe that a “real school” is where teachers teach in age-graded, self-contained classrooms (e.g., first graders learn to read; 8^th and 9^th graders take algebra) and where children and youth do what they are told. That is how students learn. Such beliefs sustain traditional forms of teaching, grant a limited amount of autonomy to teachers, and keep a complex system of many interacting parts working day in and day out.

Thus, traditional teaching, the people who enter teaching, the age-graded school, and pervasive social beliefs about what “real” teaching and “real” schools are combine to explain perennial stability in classroom practice periodically seasoned by teacher-crafted changes.

*What has kept (and keeps) classroom practice largely stable has been teacher resistance to reform.

Teacher resistance can be both active and passive: (1) many teachers actively prize what they do daily in classrooms and believe, for example, that teacher-centered instruction is more effective than student-centered instruction and judge efforts to use a new technology or curriculum to transform one to the other as uninformed. (2) Teachers resist by being minimally compliant and making small changes or do as little as possible short of insubordination because altering classroom routines substantially demand far too much teacher time, energy, and skills, given the onerous workplace conditions—class size, schedules, support staff—and the predispositions of those entering teaching. Active or passive teacher resistance keeps classroom practice on an even keel.

* What keeps teaching stable are fundamental errors in policymaker, beliefs, thinking, and actions in designing and converting policies into classroom practice.

The fundamental error in thinking policymakers make is two-fold. They believe that redesigning, dumping, or replacing key school structures—governance, organization, and curriculum–will alter teacher instruction and student learning. Secondly, they believe that public schools and classrooms are complicated not complex systems.

As a result of these beliefs, many policymakers approach structural change like mechanical engineers in designing solutions to solve system problems in schools and classrooms. They see systems as complicated structures that can broken down into discrete segments and re-engineered through algorithms and flow charts to perfection—like piloting a Boeing 737–rather than as a complex, dynamic, and yes, messy, multi-level system—air traffic controllers adapting constantly to varying weather conditions, aircraft downtime, and daily peak arrivals/departures of flights.

Surely there are structures and patterns of behavior in helping professions such as medicine, social work, and education. And just as surely these complex systems contain much uncertainty and unpredictability as hundreds of interacting and interdependent relationships and events at each level of the system (e.g., classroom, school, district) respond in varying ways to an ever-shifting environment. Unintended consequences (e.g. the accumulation of individual teacher decisions about new science lessons across the district meant that only 55 percent of teachers used newly-prescribed materials) lead to unexpected outcomes (e.g., science test scores go down). Re-engineering complex organizations like schools to alter classroom patterns of teaching and learning is doomed to failure.

Policymakers treating school system structures like clock-work gears and cogs issue directives seeking school and classroom reforms and believe that administrators and practitioners will carry out these marching orders as directed in flow charts and policy manuals. Too many loose connections, unmapped but interdependent relationships, unpredictable events, and ambiguous directives combine into a web-like complex system confounding what policymakers seek, what administrators request, and what teachers end up doing.

WHAT EXPLANATIONS FOR STABILITY AND CHANGE IN CLASSROOM PRACTICES ARE MISSING? WHICH, IF ANY, ARE MOST CONVINCING?