How to conduct an FBA, step by step

A functional behavior assessment (FBA) answers one question: what does this behavior get the student, or help the student avoid? Once the team knows that, it can teach a safer behavior that meets the same need. Without that answer, a behavior plan is a list of consequences and hope.

This page walks through the steps a school team uses, with one fictional student from start to finish. For how the FBA connects to the behavior plan and the IEP, see the FBA and BIP guide.

What you need before you start

Gather these before the first observation. Most of them take one afternoon.

• Parent consent, if your district requires it. Many states treat an individual FBA as an evaluation, which needs written consent. Check your district's procedure before you collect data.
• A short list of the people who see the behavior. Usually the classroom teacher, a special educator, a para and the family.
• Records. Office referrals, nurse visits, attendance and the current IEP. Look for times, places and classes that repeat.
• A data sheet. An ABC data form and one count sheet, such as the frequency data sheet.

Federal rules require the IEP team to consider positive behavioral interventions and supports when a student's behavior gets in the way of learning.^[1] An FBA is the usual way teams gather the information for that. It is also required in some discipline situations, covered in the FAQ below.^[2]

Step table: what each step takes

The times below are typical for one behavior in one school setting. They are planning estimates, not rules.

Step 1: Define the behavior

Pick one behavior, or one group of behaviors that serve the same purpose. Write it so two adults would mark the same thing. "Defiant" fails that test. "Tears or crumples the worksheet, or pushes it off the desk" passes.

Add a start and end rule if the behavior comes in episodes. For example: "An episode starts when the student leaves the assigned seat and ends when the student has been seated for 60 seconds." The guide to operational definitions of behavior has 16 more examples.

Step 2: Interview and review records

Interviews are the indirect part of the FBA. Ask each adult the same questions, so the answers can be compared.

• When and where does it happen most? Least?
• What happens just before it starts?
• What do adults and peers do right after?
• What does the student gain or escape when it happens?
• Are there days when it is worse, such as after a poor night's sleep or a missed breakfast?

Talk to the student too. Ask what is hard about the class, what helps and what they wish adults would do. A 4th grader may tell you "the writing is too long" faster than three weeks of data will.

Step 3: Take a baseline count

Before you change anything, measure how often or how long the behavior happens. Use frequency recording for behavior with a clear start and end. Use duration recording when episodes vary in length. Five days in the target setting is a fair minimum.

This count is the baseline the behavior plan and the IEP goal will be compared to. The guide on how to collect baseline data covers medians and ranges.

Step 4: Record ABC data

Direct observation is the core of the FBA. Each time the behavior happens, write down the antecedent (what happened right before), the behavior, and the consequence (what happened right after). Write what you saw, not what you think the student felt.

Aim for 15 to 30 incidents across different days and times. Fewer than 10 rarely shows a clear pattern. The page on how to take ABC data shows a filled-in sheet and the common recording mistakes.

Step 5: Find the pattern

Sort the ABC entries. Count how many incidents followed each type of antecedent, then each type of consequence. A simple tally is enough. Then mark the incidents on a scatterplot by time of day and class, so clusters stand out.

Look for the antecedent and consequence that show up again and again. In many FBAs, one antecedent and one consequence account for most incidents. If nothing stands out, collect more data or check whether you are mixing two behaviors with different functions.

Step 6: Write the hypothesis statement

Write one sentence the team agrees on. Use this frame: when (setting event), and (antecedent), the student (behavior), to (get or avoid something).

The four common functions are getting attention, escaping or avoiding a task or setting, getting an item or activity, and sensory or automatic reinforcement. The function of behavior entry explains each one. Name only one function per hypothesis. If the data point to two, write two.

Step 7: Test the hypothesis

A hypothesis is a best guess. Test it with one planned change before the team builds a full plan. If the function is escape from long writing tasks, shorten the task for a week and keep counting. If the count drops, the hypothesis holds. If it does not, the function may be different.

A school psychologist or BCBA may run a more formal test called a functional analysis. Most school FBAs use the simpler check above.

Step 8: Write the report

Keep the report short and readable for a parent. Include the definition, the baseline, a summary of interviews, the ABC tally, the scatterplot findings, the hypothesis, and what the team recommends. The recommendations become the behavior intervention plan.

Worked example: Marcus, grade 4

This case is fictional. The numbers show the method; they are not targets.

Referral. Marcus's teacher reports that he tears worksheets and leaves his seat "all the time." He has three office referrals since September.

Definition. "Tears, crumples or pushes a worksheet off the desk, or leaves the assigned seat without permission for more than 10 seconds during instruction."

Interviews. The teacher, the para and his mother all name writing as the hardest time. Marcus says, "The paragraphs take forever." His mother reports no problems with homework that has short answers.

Baseline. Over 5 days, Marcus had 14 episodes. Eleven happened during the 45-minute writing block, 2 in math and 1 in science.

ABC data. The team recorded 24 incidents over 2 weeks.

Nineteen of 24 incidents followed a writing demand. Seventeen ended with the task removed.

Hypothesis. "When Marcus has had a hard morning, and he is asked to write 3 or more sentences on his own, he tears the worksheet or leaves his seat, to escape the writing task."

Test. For one week, the teacher gave writing in chunks of one sentence, with a check-in after each. Episodes in the writing block fell from a median of 2 per day to 0 or 1 per day. The team kept the hypothesis and moved to the behavior plan: teach Marcus to ask for a break or a shorter chunk, and build up writing time.

Common mistakes in an FBA

• Weak: "Marcus is defiant and disruptive." Better: "Tears the worksheet or leaves the seat for more than 10 seconds during instruction."
• Weak: Five ABC entries from one bad Monday. Better: 15 to 30 entries across at least 6 different days and times.
• Weak: "Function: attention and escape and control." Better: One function per hypothesis, backed by the tally.
• Weak: Consequence written as "redirected." Better: "Teacher walked over and said 'pick it up'; task stayed on the desk." The exact consequence is what reveals the function.
• Weak: The report lists data and stops. Better: It ends with a hypothesis and specific recommendations the team can turn into a plan.

Templates and tools

• Count the behavior on the frequency data sheet, or time it on the duration data sheet.
• For behavior that is hard to count, such as off-task time, use the interval recording data sheet.
• Write the replacement skill from the replacement behavior goal templates, then paste your draft into the goal checker.
• The behavior intervention plan examples show what a plan built from each function looks like.

The IRIS Center offers a free training module on FBA for school teams.^[3]

Frequently asked questions

Use it in IEP Atlas

• FBA in the IEP glossary
• Function of behavior in the IEP glossary
• Frequency data sheet
• Replacement behavior goals
• IEP goal checker

Related guides

• FBA and BIP: a practical guide for IEP teams
• How to take and analyze ABC data
• Operational definitions of behavior: examples
• BIP examples by function
• Behavior hypothesis statement examples
• Writing a behavior goal from an FBA
• FBA template: interviews, observations, hypothesis

Sources

1. 34 CFR §300.324: Development, review, and revision of IEP, Legal Information Institute, Cornell Law School
2. 34 CFR §300.530: Authority of school personnel, U.S. Department of Education (IDEA website)
3. Functional Behavioral Assessment: Identifying the Reasons for Problem Behavior and Developing a Behavior Plan, IRIS Center, Vanderbilt University

Written and checked by the IEP Atlas editorial team under our editorial policy. This guide describes general practice and federal rules. It is not legal advice; your state may add requirements, and the IEP team makes the decisions for each student.