Function of Student Behavior

  • Function Based Thinking (FBT)


    Function Based Thinking (FBT) is a model for thinking and a systematic process for defining problem behaviors and selecting interventions that match the function of the behavior.  FBT considers why the student is having the problem behavior and what they need.  Using FBT, we hypothesize the following questions:  What does the behavior mean?  What does the student need?  What skills are missing?


    Three Steps of FBT

    1. Gather information
      1. Define the behavior in observable and measurable terms
      2. Describe the antecedents
        1. What happened immediately before the behavior
        2. When, where, and with whom is the behavior most likely and least likely to occur (focus on elements you can control within your classroom)
      3. Describe the consequences
        1. Consequences are what occurs immediately following the behavior
        2. Consequences will either increase or decrease the likelihood that the behavior will occur again
      4. Analyze the data
        1. Identify trends
        2. Utilize an ABC approach to accurately define the problem
      5. Develop a plan
        1. Determine the function
          1. Investigate why the behavior is occurring
          2. The function of behavior falls into two large categories: to get something or to avoid something
    • Write a hypothesis, which allows you to look at the variables that are under your control
    1. Select a replacement behavior
      1. Identify skill deficits related to the behavior
      2. Identify an alternative, more desirable behavior for the student to perform instead of the problem behavior
        1. Select a replacement behavior that serves the same function as the problem behavior
      3. Develop a plan for instruction
        1. Teach replacement behavior (shape the behavior, provide reinforcement, change environmental antecedents and consequences)
      4. Evaluate and monitor the plan
        1. Collect data to determine if your plan is working


    Antecedent – Behavior – Consequence Data

    Antecedent Behavior Consequence

    Functions of Behavior:

    Functions of Behavior

    ABCs and Functions of Behavior

    Images (ABC and functions of behavior) and steps of FBT taken from



    Defining Behavior

    Operationally Defining Behavior: Target and Replacement behaviors