Creating a Theory of Improvement:

The Basics of Phase 2

What is the purpose of this phase?

You will help set your team up for success by creating a theory of how the problem can be solved before moving to action.

When should this happen?

After you have analyzed your problem.

Who is involved?

The improvement team leader and all team members.

What will you do?

Build a driver diagram to create a working theory of improvement. Revise your driver diagram, if and when necessary.

You are ready for Phase 2 when you have:


defined your problem clearly and crafted a problem statement


gained new insight and understanding about the problem, identifying specific causes and underlying issues that you as a team have not explicitly focused on before


completed the Problem Statement Readiness Check from Phase 1 to consolidate your thinking around the factors affecting your problem


generated a list of possible actions you predict will have influence on your problem

Key Terms

definition of working theory of improvement

Working theory of improvement

Articulates a hypothesis which outlines exactly how you see changes in practice sparking improvement and providing a conceptual bridge from your analysis of the problem to action in the real world.

Driver diagram

Visual representation that turns a team’s understanding of a problem into a theory of the changes that must take place in order to accomplish the aim.


High-leverage areas you believe play an essential role in influencing your aim. Drivers cannot be controlled directly; each is influenced by dozens of smaller steps you can take over the next several months to achieve your aim.

Primary drivers

The essential, big-picture areas that drive progress toward the aim. They are “what” must happen to get to your aim. 

Secondary drivers

The sub-factors that influence each of the broader primary drivers. They are “where” you might change your practice to improvement in your primary driver.

Change ideas

The small tweaks to classroom practice or materials that can be tested over a short period of time. 

Aim statement

Defines the improvement your team is trying to accomplish written as a S.M.A.R.T. goal.

S.M.A.R.T. goal

A goal that is Specific, Measurable, Aspirational but attainable, Relevant, and Time-bound. 

Creating a Theory of Improvement:
Summary of the Concepts

After spending weeks analyzing your problem, a sense of urgency may build, leaving your team ready to start making changes. Phase 2 is designed to prevent us from haphazardly jumping into action. Instead, consolidate your team’s collective thinking into a hypothesis that enables clear starting points for improvement efforts. The working theory of improvement is arrived at through the use of a tool called a driver diagram. A driver diagram takes your best understanding of how a system functions in practice and puts down on paper your best ideas for improving it.

Building this theory with your team will uncover clear starting points where you should begin your improvement efforts and make visible the collective thinking behind your hypothesis. Later on, it will suggest data you can collect to verify progress and provide a place to record the learning that occurs as your test your ideas in practice. By taking the time to name your theory and incorporate the multiple perspectives on your team, you will create a stronger theory that can continue to be refined as your understanding grows.

A good theory is based on a broad and diverse understanding of the problem. Consider including:

  • the considerations of diverse stakeholders within your school community, like teachers, parents, and support staff.
  • the experiences of those outside the community, like other education professionals, and talk to them as you develop your theory.
  • existing research and resources on proven practices.

Understanding the Driver Diagram

driver diagram

There are three key parts to a driver diagram.


1. Aim Statement 

  • This headlines your theory of improvement and answers the overarching question, “What are we trying to accomplish?”
  • It is a specific statement of the long-term outcomes you expect. It should follow the protocol for a S.M.A.R.T. goal: Specific, Measurable, Aspirational but attainable, Relevant, and Time-bound.
  • Aims are long-term goals, often too ambitious to be accomplished in one year, and more likely achieved over a 2–5 year range.
example of aim statement

2. Drivers

  • Drivers are high-leverage areas that play an essential role in influencing your aim.
  • Each driver represents a category of possible factors that affect your aim; drivers cannot be controlled directly but can be achieved through other actions.
  • Primary drivers are the broad categories for thinking about the factors that can get you to your aim, whereas secondary drivers are the sub-factors, like the tangible opportunities you have every day to tweak your classroom practice.

         Click on the examples to make them bigger.

    aim and primary driver diagram
    Primary versus secondary drivers explanation


    3. Change Ideas 

    • Change ideas are the small changes or tweaks in your classroom practice that impact secondary drivers.
    • Change ideas are a good place to integrate existing research or proven practice into your working theory.
    • These are the changes we test, reflect on, and iteratively improve during the improvement science process.
      explanation of change ideas

      Putting It All Together

      Driver diagrams come in many shapes and sizes. It will serve your team well as long as it makes sense and contains logical connections that map from change ideas all the way through to the aim. Below is an example of what it could look like when we put it all together.

      example of a completed driver diagram

      Checking Your Theory of Improvement

      It can be helpful to check your newly drafted working theory of improvement. One way to check your thinking is to fill in the sentence prompt below. Look at a single horizontal row of the driver diagram; if your ideas mesh into coherent, exciting sentences, chances are you have created a driver diagram that outlines a working theory of improvement with a high-leverage change idea to begin testing. Read across your driver diagram using a single row.

      blank sentence prompt check
      example of completed sentence prompt check

      A second way to check the connections between components is by using “why” and “how” prompts. Reading from right to left, each connection should answer the question “why?” while reading from left to right, each connection should answer the question “how?”

      right to left check
      left to right check

      These techniques should help you look for gaps or leaps in logic in your theory, and are helpful for beginners to make sense of the diagram. Remember that while your driver diagram should make sense and generate consensus among the team, it doesn’t need to be perfect. A driver diagram is always a work in progress. You can and should revise it as you learn more.

      Overview of the Tools

      crafting an aim statement tool image
      driver diagram
      empathy map graphic organizer

      Crafting an Aim Statement

      60 minutes

      What is it? A S.M.A.R.T. goal that articulates the improvement your team is working toward.

      What does it do? Provides a common goal to link together the efforts and innovations of your team over the next few months.

      Why use it? It is the articulation of what your team is trying to achieve. Without it, your work will lack focus and success will be difficult to measure.

      Driver Diagram

      60 minutes

      What is it? A visual representation of your team’s understanding of the problem and a map of potential approaches to your improvement.

      What does it do? Provides an overview of your hypothesized solutions and allows you to narrow your focus on high-leverage areas.

      Why use it? It enables your team to decide on the most strategic path to pursue your improvement.

      Revising Your Driver Diagram 

      60 minutes

      What is it? Guidance on how to revise your driver diagram as your thinking evolves.

      What does it do? Ensures your driver diagram stays current and accurately reflects the most up-to-date thinking about your problem.

      Why use it? To capture and name the parts of your evolving hypothesis, especially if you’re going to share with others outside of your team.