If a Student Can Do It Sometimes, Do They Really Have a Skill Deficit?

This is one of the most important questions we can ask in school-based OT. A student writes beautifully at home but produces nearly illegible work at school. A child completes an assignment when an adult sits beside them but struggles when expected to work independently. A student can perform a task during an OT session but doesn’t seem able to do the same thing in the classroom. Is it a skill deficit or performance barrier?

The temptation is to jump to one of two conclusions:
“They can’t do it.”
or
“They can do it—they just won’t.”
Dr Aditi the OT - Skill Deficit or Performance Barrier Poster of confused and frustrated student
I don’t think either conclusion gives us enough information.

The more useful question is:

What changes between the times the student succeeds and the times the student struggles?

Recent occupational therapy and education research increasingly supports looking beyond the child alone. Task demands, physical and social environments, executive functions, available supports, and the context in which performance occurs can all influence school participation and performance (Maciver et al., 2023; Meuser et al., 2023; Ruffini et al., 2023).

That is the reasoning behind Decision Tree No. 02 – Is this a Skill Deficit or Performance Barrier?

The Skill Deficit vs. Performance Barrier Decision Tree

Dr Aditi the OT - School OT Decision Tree helping practitioners distinguish a skill deficit from a performance barrier by comparing performance across tasks, supports, environments, and conditions.

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    This Decision Tree begins with a very common school problem:
    A student completes a school task inconsistently, slowly,
    or only with significant adult support.
    Instead of immediately deciding why, we start gathering information.
    1. Can the student complete the task successfully under supportive or ideal conditions?
    If the answer is no, there may genuinely be a skill gap.

    That might involve:
    • motor skills
    • visual-motor abilities
    • sensory processing
    • cognition
    • communication
    • task understanding
    • handwriting
    • or another skill required for successful participation
    But if the answer is yes, something important has just been established:

    The student has demonstrated at least some capacity to perform the task.

    Now we need to determine what is helping—or interfering—with that performance.
    2. Does performance improve when conditions change?
    What happens when we add:
    • structure,
    • modelling,
    • reduced task demands,
    • environmental changes,
    • visual supports,
    • regulation support,
    • additional time,
    • or another reasonable accommodation?
    If performance improves, that tells us something useful.

    Rather than continuing to remediate the same supposed deficit, identify which support changed performance.

    Use it consistently. Measure the outcome. Then reduce the support gradually if and when that is appropriate.
    3. What if support doesn’t immediately solve the problem?
    Then I widen the lens.

    Compare the student’s performance across:
    • people,
    • tasks,
    • environments,
    • times of day,
    • levels of independence,
    • and types of demand.
    And consider:
    • fatigue,
    • pain,
    • anxiety,
    • attention,
    • communication,
    • task meaning,
    • executive-function demands,
    • competing demands,
    • and environmental expectations.
    The Decision Tree includes an important reminder:

    Do not label a difficulty as “noncompliance” until skill, access, regulation, communication, and environmental demands have been examined.

    That may be the most important line on the entire page.

    My Story: The IEP Meeting That Changed How I Thought About This

    I was sitting in an IEP meeting for a middle school student whose parents were requesting OT because of handwriting concerns. They explained that his handwriting was very messy and sometimes nearly illegible.

    So I asked a simple question:

    “Is it always like that—or is he rushing?”

    They said he often rushed at school. Then they added something important. When the teacher sent the same work home and he completed it there, his handwriting was fine.

    That stopped me.

    Because now the question wasn’t simply:

    “Can this student write legibly?”

    We already had evidence that he could.

    The question became:

    “Why isn’t that same skill consistently showing up at school?”

    At the time, I thought about it as a “can’t do versus won’t do” distinction.

    But over the years, I’ve become much more careful with that language.

    What looks like “won’t” may actually reflect a mismatch between the student, the task, the demands, and the environment.

    That IEP meeting stayed with me. It was one of the experiences that made me want to write more about the difference between skill acquisition and actual performance.

    And it changed one of the first questions I ask:
    Show me when the student CAN do it.
    That often tells us just as much as looking at when they can’t.

    Why “Can’t Do vs. Won’t Do” Is Too Simple

    The phrase is appealing because it sounds straightforward.

    Can’t do = skill problem.
    Won’t do = behaviour problem.

    Except students aren’t quite that straightforward. A student may possess a skill and still be unable to consistently access it when:
    • the task becomes longer,
    • the pace increases,
    • attention demands rise,
    • several skills must be coordinated simultaneously,
    • anxiety increases,
    • the environment becomes distracting,
    • fatigue sets in,
    • instructions are unclear,
    • or the task has little meaning for the student.
    That isn’t the same thing as saying the student cannot perform the skill.

    But it also isn’t necessarily fair to say:

    “They can. They’re simply choosing not to.”

    That’s why I prefer the language used in this Decision Tree:
    Skill Deficit vs. Performance Barrier
    A skill deficit suggests that the student has not yet acquired or developed the skill sufficiently. A performance barrier asks a broader question:

    What is preventing an existing or emerging skill from being demonstrated successfully in this particular situation?

    That framing keeps us curious rather than judgemental.

    What Recent Research Tells Us

    1. Handwriting Performance Can Change Depending on the Task
    This finding relates directly to my middle-school IEP story.

    Fogel et al. (2022) examined handwriting legibility in 148 school-aged children ages 9–14 across three different writing conditions:
    • copying in their best handwriting,
    • copying quickly,
    • and free writing.
    The children’s handwriting was not equally legible across those tasks.

    Performance was best during the “copy-best” condition and poorer when writing quickly and during free-writing tasks, where students had to manage additional cognitive demands while producing written work (Fogel et al., 2022).
    What This Means at School
    Imagine evaluating the student from my IEP meeting using only his rushed classroom worksheet.

    You might conclude:

    “He has poor handwriting.”

    Now imagine evaluating only the careful work he completed at home. You might conclude:

    “His handwriting is fine.”

    Neither sample tells the complete story. The discrepancy itself is information.

    Ask:

    What changed?

    Perhaps it was:
    • pace,
    • time available,
    • competing cognitive demands,
    • environment,
    • teacher proximity,
    • task complexity,
    • motivation,
    • or fatigue.
    That’s why I want more than one writing sample.
    2. Environment Is Part of Performance—not Background Noise
    Meuser et al. (2023) conducted a scoping review of school-environment interventions designed to support participation for children with special educational needs.
    Their findings emphasised that children’s participation is influenced by both the social and physical school environment. They also highlighted occupational therapists’ expertise in matching a student’s needs with task requirements and environmental conditions (Meuser et al., 2023).
    What This Means at School
    If performance improves when we change:
    • seating,
    • directions,
    • visual supports,
    • amount of work,
    • adult assistance,
    • classroom distractions,
    • timing,
    • or task structure,
    That is not cheating. That is data.

    The change tells us something about the conditions the student needs in order to participate successfully.

    Our next question becomes:

    Which part of that support was actually helping?
    3. Participation Reflects More Than the Student’s Diagnosis or Skills
    Maciver et al. (2023) examined school participation in 688 children with additional support needs, based on reports from 252 teachers.

    Participation was associated with multiple factors, including children’s competence, environment, identity, symptoms, language, and level of school support (Maciver et al., 2023).
    What This Means at School
    Performance is rarely explained by one variable.
    When a student is struggling, I don’t want to reduce that student’s performance to:
    “fine motor weakness”
    or
    “behaviour”
    or
    “motivation”
    I want to look at the interaction between:
    student + task + environment + supports.
    Sometimes the student needs intervention.
    Sometimes the task needs modification.
    Sometimes the environment needs modification.
    And often, we need a bit of all three.
    4. Executive Functions Can Affect Writing Performance
    Writing isn’t simply a motor task.

    Ruffini et al. (2023) studied 175 children in Grades 3–5 and examined executive functions alongside reading and writing performance in paper and digital conditions.

    Executive-function skills—including working memory and cognitive flexibility—were associated with aspects of students’ writing performance, and lower-performing writers differed from stronger writers in several executive-function measures (Ruffini et al., 2023).
    What This Means at School
    A student may know how to form letters perfectly well and still produce poor handwriting during a complex classroom assignment.

    Why? Because now the student has to:
    • remember what to write,
    • organise ideas,
    • spell,
    • monitor grammar,
    • follow directions,
    • manage time,
    • ignore distractions,
    • and produce handwriting,
    all at once.

    That is quite different from:

    “Copy this sentence neatly for me.”

    The more complex the task becomes, the more likely we are to expose a performance barrier that isn’t simply a handwriting skill deficit.
    5. Attention, Behaviour, and Environment Interact
    Kaya Kara et al. (2023) examined participation and environmental factors among 83 children with ADHD.

    Inattention was associated with involvement in home and school activities, and the authors concluded that improving participation may require addressing both the cognitive and behavioural demands of activities while also modifying environmental supports (Kaya Kara et al., 2023).

    This study involved children with ADHD, so I would not generalise its findings to every student. But the principle is useful and important.
    What This Means at School
    What looks like:

    “He knows how to do it but won’t.”

    may warrant several more questions before we reach that conclusion.
    Is the student:
    • distracted?
    • overwhelmed?
    • anxious?
    • fatigued?
    • struggling to initiate?
    • managing too many demands simultaneously?
    • having difficulty sustaining attention?
    • unclear about expectations?
    Behaviour is information.

    It isn’t automatically an explanation.

    What I Look for as a School OT

    When performance is inconsistent, my first instinct is to compare conditions.

    I want to know:
    1. Can the student ever do it?
    This is my starting point.

    Show me:
    • the best handwriting sample,
    • the successful classroom task,
    • the assignment completed independently,
    • the work completed at home,
    • the activity the student enjoys,
    • or the situation in which adults say, “He does this perfectly.”
    That successful performance matters.

    It gives us a comparison condition.
    2. What is different when the student succeeds?
    Compare: successful condition vs. difficult condition.

    Look at:
    • task length,
    • task complexity,
    • pace,
    • noise,
    • seating,
    • distractions,
    • adult support,
    • visual supports,
    • writing demands,
    • time of day,
    • fatigue,
    • interest,
    • anxiety,
    • peer demands,
    • and expectations.
    Sometimes one difference jumps out.

    Sometimes several do.
    3. What happens if I reduce support?
    This is important.

    Suppose a student performs beautifully when an adult sits beside them. That doesn’t necessarily prove a skill deficit. It may tell us the adult is providing:
    • initiation cues,
    • pacing,
    • reassurance,
    • organisation,
    • redirection,
    • or accountability.
    Now gradually reduce that support.

    Can the student maintain performance?

    That tells me much more.
    4. Does the problem follow the student—or the task?
    If handwriting is poor:

    in every class, at home, during OT, during testing, and even when the student is trying their best, I’m more suspicious of a genuine skill deficit.

    If handwriting deteriorates:

    only during lengthy assignments, only when rushing, or only in certain environments, I start looking hard at performance conditions.
    5. What is the educational impact?
    Ultimately, I care about participation.

    Is the difficulty preventing the student from:
    • completing assignments?
    • communicating knowledge?
    • keeping pace?
    • accessing the curriculum?
    • demonstrating learning?
    • participating independently?
    That is much more relevant than simply deciding whether a student could theoretically perform the skill.

    What to Try Before Adding More Intervention

    1. Change One Variable
    Rather than changing everything at once, change one meaningful condition.
    For example:

    Original task: Write 15 sentences independently.
    Trial: Write five sentences using the same handwriting expectations.
    Did performance change?

    Or:

    Original: Independent work.
    Trial: Visual checklist provided.
    Did performance change?

    Changing one variable helps us understand what is actually influencing performance.
    2. Compare Work Across Settings
    This is exactly what happened in my IEP meeting.

    Ask for:
    • classroom samples,
    • homework,
    • tests,
    • journal writing,
    • copying,
    • free writing,
    • and work completed under different levels of support.
    Don’t view inconsistent performance as inconvenient data.

    The inconsistency is the data!
    3. Trial Structure Before Assuming a New Skill Needs to Be Taught
    Try:
    • visual directions,
    • a checklist,
    • shortened chunks,
    • a model,
    • predictable breaks,
    • a timer,
    • reduced copying,
    • or clearer expectations.
    If performance improves substantially, ask: What did that support change?

    Meuser et al. (2023) found that supportive teaching approaches and environmental adaptations are important components of school participation interventions.
    4. Look at Task Meaning
    This one gets missed.

    Students aren’t robots. A student may invest far more effort into an activity that feels meaningful than into repetitive written work.

    That doesn’t automatically make the problem behavioural. It tells us something about engagement. School engagement includes not only observable participation but also emotional and cognitive involvement in school activities (Tam et al., 2023).

    So ask:

    Does performance change depending on the purpose of the task?
    5. Collaborate With the Teacher
    This is where school OT is particularly valuable. We don’t need to recreate the classroom in the therapy room. We already have a classroom.

    Meuser et al. (2024) described context-based collaboration between teachers and occupational therapists as a process in which both professionals learn together and collaboratively apply strategies that support children’s inclusion and participation.

    Sometimes the most useful OT intervention isn’t another pull-out session.
    It is standing beside the teacher and asking:

    “What changes right before his performance falls apart?”

    When It May Actually Be a Skill Deficit

    A skill deficit becomes more likely when the student:
    • cannot perform the task even under supportive conditions,
    • demonstrates the same difficulty across multiple settings,
    • struggles despite modelling and appropriate instruction,
    • requires significant assistance with the actual component skill,
    • does not show the skill even when motivated and well supported,
    • and demonstrates a consistent pattern rather than context-specific difficulty.
    Then I want to identify the specific component that is limiting performance.

    For handwriting, perhaps that is:
    • letter formation,
    • automaticity,
    • motor coordination,
    • visual-motor demands,
    • speed,
    • endurance,
    • or another handwriting-related skill.
    But I don’t want to start treating “handwriting” until I know what part of handwriting isn’t working.

    When It Looks More Like a Performance Barrier

    A performance barrier becomes more likely when the student clearly demonstrates the skill under some conditions but performance changes substantially according to:
    • task length,
    • pace,
    • adult support,
    • environment,
    • attention demands,
    • regulation,
    • fatigue,
    • anxiety,
    • task complexity,
    • or competing demands.
    That does not mean:

    “The student knows how to do it, so this isn’t an OT issue.”

    It means our intervention target may need to shift. Instead of teaching a skill the student already possesses, perhaps we need to improve:
    • access,
    • independence,
    • endurance,
    • task setup,
    • environmental fit,
    • self-regulation,
    • routines,
    • or strategy use.
    That distinction can save an enormous amount of unnecessary intervention.

    Before You Call It “Noncompliance”

    This deserves its own section. When a student does something sometimes but not consistently, it is incredibly easy for adults to conclude:

    “He just won’t do it.”

    Sometimes motivation or reinforcement certainly can influence performance. But I would not use “won’t” as my clinical conclusion until I have looked at:
    • Skill
    • Access
    • Regulation
    • Communication
    • Environment
    • Attention
    • Fatigue
    • Pain
    • Anxiety
    • Task demands
    Only then do we have enough information to begin understanding what the behaviour may be communicating. The wording matters because our interpretation determines our intervention.

    If we assume a student can’t, we may keep teaching a skill they already have.
    If we assume a student won’t, we may respond behaviourally to a child who is actually overwhelmed by the demands.

    Neither is particularly helpful. Assess before you assume.

    Does This Student Need OT?

    Maybe.

    But inconsistent performance alone isn’t enough to answer that question. Consider two students.
    Student A
    The student cannot produce legible handwriting even when:
    • given additional time,
    • working in a quiet environment,
    • copying a short model,
    • receiving appropriate cues,
    • and clearly trying to write carefully.
    There may be a genuine handwriting skill deficit worth investigating.
    Student B
    The student produces nearly illegible work during rushed classroom assignments but writes legibly when:
    • given time,
    • expectations are clear,
    • work is broken into manageable pieces,
    • or the same assignment is completed at home.
    That student presents a different clinical question. The intervention might involve:
    • pacing,
    • environmental support,
    • task modification,
    • self-monitoring,
    • consultation,
    • executive-function strategies,
    • or classroom routines rather than remediation of basic handwriting mechanics.
    The student’s work may look identical on the first worksheet.

    The reason behind it may be completely different.

    The Bottom Line

    When a student performs inconsistently, don’t rush to decide:

    “can’t do”
    or
    “won’t do.”

    Instead, ask:

    Can the student do it under supportive conditions?
    What changes when performance improves?
    What changes when performance deteriorates?
    Is the problem the skill—or the conditions required to access the skill?

    Recent research supports this broader view of school performance. Handwriting changes according to task demands; executive functions contribute to writing; and children’s participation reflects an interaction among competence, environment, supports, and activity demands (Fogel et al., 2022; Maciver et al., 2023; Meuser et al., 2023; Ruffini et al., 2023).

    My School OT Takeaway

    Don’t just ask whether the student can do it. Ask when they can do it—and what’s different when they can’t.

    That difference may tell you exactly where to intervene.

    Get the Skill Deficit vs. Performance Barrier Decision Tree

    Have a student whose performance seems to change from one situation to the next?
    Use the Decision Tree to organise the questions before deciding whether the student needs skill remediation, environmental support, or a closer look at other barriers.

    Get the Next School OT Decision Tree

    School-based OT rarely gives us tidy yes-or-no answers. That’s why I created Decision Tree Tuesday—one practical clinical reasoning tool at a time, built around the real questions that come up in school-based practice.

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    Looking for practical school-based OT templates, decision-making tools, and resources?

    References

    Fogel, Y., Rosenblum, S., & Barnett, A. L. (2022). Handwriting legibility across different writing tasks in school-aged children. Hong Kong Journal of Occupational Therapy, 35(1), 44–51. https://doi.org/10.1177/15691861221075709

    Kaya Kara, O., Kara, K., Dogan, M., Tascioglu, E. N., Kose, B., Cetin, S. Y., Sahin, S., & Anaby, D. (2023). How cognitive and behavioural body-functions of children with ADHD are linked to their participation and environmental supports? Research in Developmental Disabilities, 141, 104592. https://doi.org/10.1016/j.ridd.2023.104592

    Maciver, D., Singh Roy, A., Johnston, L., Tyagi, V., Arakelyan, S., Kramer, J. M., Richmond, J., Romero-Ayuso, D., Nakamura-Thomas, H., SPQ Study Group, Todorova, L., van Hartingsveldt, M., & Forsyth, K. (2023). Participation-related constructs and participation of children with additional support needs in schools. Developmental Medicine & Child Neurology, 65(4), 498–508. https://doi.org/10.1111/dmcn.15390

    Meuser, S., Borgestig, M., Lidström, H., Hennissen, P., Dolmans, D., & Piskur, B. (2024). Experiences of Dutch and Swedish occupational therapists and teachers of their context-based collaboration in elementary education. Journal of Occupational Therapy, Schools, & Early Intervention, 17(1), 37–53. https://doi.org/10.1080/19411243.2022.2143465

    Meuser, S., Piskur, B., Hennissen, P., & Dolmans, D. (2023). Targeting the school environment to enable participation: A scoping review. Scandinavian Journal of Occupational Therapy, 30(3), 298–310. https://doi.org/10.1080/11038128.2022.2124190

    Ruffini, C., Tarchi, C., & Pecini, C. (2023). Which executive functions affect text comprehension and writing in paper and digital mode? An investigation in primary school children. Computers & Education, 207, 104936. https://doi.org/10.1016/j.compedu.2023.104936

    This article is intended for educational purposes. Clinical and educational decisions should be individualised to the student, the task, the educational environment, and the findings of the multidisciplinary team.

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