Why the Discrepancy Model Fails Our Students

And what Down syndrome can teach us about expectations

For decades, the discrepancy model has dominated how we identify learning disabilities. We compare a child’s IQ to their academic achievement, and if there’s a significant gap–if their “intellectual potential” is much stronger than their academic skills–we assume they have a learning disability worthy of intervention. If there’s no gap, the child is just functioning at a level consistent with their intelligence.

I’ve come to believe this model is not just flawed; it’s harmful.

First, let’s acknowledge the simplest issue: the discrepancy model isn’t supported by research. But there’s a deeper issue that cuts to the heart of educational equity and disability rights. The discrepancy model operates on a dangerous assumption about human potential. When we say that a child with a low IQ score and low academic achievement doesn’t have a “real” learning disability—that they’re simply performing “as expected”—we’re essentially saying, We already know what this child is capable of, and it isn’t much.

This should trouble us deeply.

Yes, IQ correlates with academic achievement. But the correlation is far less strong than many of us assume, especially when we factor in the self-fulfilling nature of our expectations.

The history of Down syndrome offers a powerful illustration of what happens when we let our assumptions about ability limit our beliefs about what’s achievable.¹

For most of the 20th century, people with Down syndrome were systematically underestimated. The prevailing wisdom was that they were incapable of meaningful learning, independence, or contribution to society. Based on these assumptions, children with Down syndrome were routinely institutionalized. They received poor care, minimal education, and virtually no opportunities for employment or independent living. And unsurprisingly, under those conditions, they accomplished little.

But, over time, families began advocating differently. Researchers began questioning old assumptions. Educators began trying new approaches. Expectations began to rise. And people with Down syndrome rose to meet them.

Today, with high expectations and appropriate support, people with Down syndrome are accomplishing things that would have been considered impossible just a few decades ago. They’re attaining high levels of education, holding competitive jobs, living independently, and contributing meaningfully to their communities. The capabilities were always there; what changed was our willingness to see and nurture them.

But the starting point is assuming that achievement is not only possible but likely. If we approach children with the assumption that their potential is already known and limited, we lower our expectations, reduce our instruction, and accept minimal progress as inevitable, and then we point to the minimal progress as proof that we were right all along. On the flip side, if we approach any child—regardless of test scores, diagnosis, or apparent limitations—with the assumption that meaningful growth is within reach, we create the conditions for that growth to occur.

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As noted in the comments, this is proof that the last draft isn’t always the best!

1. https://www.globaldownsyndrome.org/about-down-syndrome/the-story-of-two-syndromes/